I’m excited to share my Rhubarb Oat Bars recipe, where tart rhubarb and wholesome oats meet a touch of cinnamon for a sweet and tangy treat worth saving and sharing.

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I didn’t expect a bar to change my week but these Oatmeal Rhubarb Bars did. Tart fresh rhubarb peeks through an oat crumble, and the texture is weirdly addictive, like breakfast pretending to be dessert.

I kept nibbling pieces while I tested because the contrast of bright rhubarb and chewy oats just works, trust me. If you like Rhubarb Dessert Bars that are easy enough to pack for lunches yet fancy enough for company, you’re gonna want to save this.

It’s simple but not boring, you’ll notice little surprises in every bite.

Ingredients

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Tart stalks give bright sour bite, low calorie, vitamin C and fiber
Old fashioned oats add chewy texture, good fiber and complex carbs for slow energy
Packed brown sugar brings warm caramel sweetness adds moisture but boosts simple carbs
Cold butter makes crumbly topping, rich flavor and saturated fat so use sparingly
All purpose flour gives structure and chew, mostly starch carbs with little protein
Lemon juice adds bright acidity to tame rhubarb, tiny vitamin C, sharp sour note
Cinnamon is a warm spice that tricks your tongue into more sweetness, tiny antioxidants

Ingredient Quantities

1 lb fresh rhubarb about 3 cups

3/4 cup granulated sugar

2 tablespoons cornstarch

1 tablespoon lemon juice

1/2 teaspoon vanilla extract (optional)

1/2 teaspoon ground cinnamon

1 1/2 cups old fashioned rolled oats

1 1/2 cups all purpose flour

1 cup packed light brown sugar

1/4 cup granulated sugar

1/2 teaspoon fine salt

3/4 cup (12 tablespoons) cold unsalted butter cubed

How to Make this

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1. Preheat oven to 350 F (175 C). Line an 8×8 inch pan with parchment leaving an overhang, or grease it well so bars can be lifted out later.

2. Trim and chop about 1 lb rhubarb into 1/2 inch pieces, you should have roughly 3 cups.

3. In a medium saucepan toss the rhubarb with 3/4 cup granulated sugar, 2 tablespoons cornstarch, 1 tablespoon lemon juice, 1/2 teaspoon vanilla extract (optional), and 1/2 teaspoon ground cinnamon. Let sit 5 to 10 minutes so the sugar draws out some juice.

4. Cook the rhubarb mixture over medium heat, stirring often, until it thickens and becomes glossy and bubbly, about 5 to 8 minutes. Taste and add a little extra sugar if it seems too tart. Remove from heat and let cool while you make the crust.

5. In a large bowl combine 1 1/2 cups old fashioned rolled oats, 1 1/2 cups all purpose flour, 1 cup packed light brown sugar, 1/4 cup granulated sugar, and 1/2 teaspoon fine salt. Sprinkle the 3/4 cup (12 tablespoons) cold unsalted butter cubes over the dry mix.

6. Use your fingers, a pastry cutter, or a food processor to cut the butter into the dry mix until it resembles coarse crumbs and holds together when pressed, about pea sized bits and some larger flakes. If it gets too warm chill for a few minutes.

7. Press about two thirds of the oat mixture firmly into the prepared pan to form an even bottom crust. Reserve the rest for the topping. You want a compact base so the bars slice cleanly.

8. Bake the crust alone for 12 to 15 minutes until it starts to set and the edges are lightly golden. This keeps the filling from making the crust soggy.

9. Spread the cooled rhubarb filling evenly over the hot crust, then sprinkle the remaining oat mixture over the top, gently pressing a bit so it sticks. Bake 25 to 30 minutes until the top is golden and the filling is bubbling at the edges.

10. Cool completely in the pan on a wire rack, at least 2 hours so the filling sets. Use the parchment to lift out and cut into bars. Store in the fridge up to 5 days or freeze for longer.

Equipment Needed

1. 8×8 inch baking pan, lined with parchment or greased so the bars lift out easy
2. Parchment paper, with an overhang for lifting
3. Medium saucepan for cooking the rhubarb
4. Large mixing bowl for the oat crust
5. Measuring cups and spoons, for accuracy
6. Sharp knife and cutting board to chop the rhubarb
7. Pastry cutter or food processor, or just use your fingers to cut in the butter
8. Wooden spoon or rubber spatula for stirring and spreading
9. Wire cooling rack so the bars cool completely
10. Oven mitts, safety first

FAQ

Q: Can I use frozen rhubarb? A: Yes, totally. Thaw it, drain off extra liquid and pat dry a bit. Frozen rhubarb tends to be wetter so add an extra teaspoon or two of cornstarch if it looks soupy after thawing.

Q: How do I keep the bars from getting soggy? A: Press the oat crust firmly so it holds, use the cornstarch in the filling, and bake until filling bubbles and top is golden. Cool completely and chill for at least an hour before cutting, dont cut them hot or theyll collapse.

Q: Can I make these gluten free or dairy free? A: Yes. Swap the all purpose flour for a 1:1 gluten free flour and use certified gluten free oats. For dairy free, use solid coconut oil or a vegan butter in the same amount as the cold butter. Texture might be slightly different but still good.

Q: How should I store or freeze the bars? A: Room temp for 1-2 days, refrigerated up to 4-5 days in an airtight container. Freeze up to 3 months, wrapped well. Thaw in the fridge then bring to room temp or warm briefly in the oven to crisp the top.

Q: Why do you use cornstarch and that much sugar? A: Cornstarch thickens the rhubarb juices so the bars set and dont run. The sugar balances the tart rhubarb, you can cut back a bit if you like tangier bars but they may be less set and more tart.

Q: Any tips for cutting neat squares and serving? A: Line the pan with parchment and lift the whole slab out to cut. Chill first, use a sharp knife dipped in hot water and wiped dry between cuts, or use a serrated knife and a gentle sawing motion. Serve with whipped cream or vanilla ice cream if you want, its great warm or chilled.

Delicious Oatmeal Rhubarb Bars Recipe Substitutions and Variations

Rhubarb: frozen rhubarb (thaw and drain) is an easy swap, or use tart apples, peeled and diced (toss with 1 Tbsp lemon to keep brightness), or strawberries, but reduce the sugar a bit
Cornstarch: arrowroot powder is a 1:1 replacement, tapioca starch also works 1:1, or use all purpose flour at about double the cornstarch amount and cook the filling a few extra minutes to thicken
Old fashioned rolled oats: quick oats can replace 1:1 though bars will be softer, or use gluten free rolled oats if needed, or pulse rolled oats briefly in a food processor for a finer crumb
Cold unsalted butter: cold solid coconut oil can be used 1:1 (gives a mild coconut note), chilled vegetable shortening 1:1 makes a crumblier bar, or use salted butter and cut back the added salt slightly

Pro Tips

1) Taste and tweak the sweetness as you go. Rhubarb varies a lot, so start with less sugar, cook the filling, then taste it warm. If it still feels too tart add sugar a little at a time, dont dump it in all at once or the bars will be cloying.

2) Keep the butter cold and vary the crumb size for texture. Work the butter in until you have mostly pea sized bits with some bigger flakes for chew, and if your hands warm it too much chill the mix for 10 minutes. Cold butter = better crunchy topping and a firmer crust.

3) Prevent a soggy bottom by prebaking and letting the filling cool before adding it. Also press the crust firmly into the pan so it compacts, that helps slices hold together instead of falling apart when you cut them.

4) Chill fully then slice with a hot, wiped knife for clean bars. Cool at room temp first, then pop in the fridge if you want extra firm bars. Leftovers keep well chilled or frozen, just thaw in the fridge before serving.

Delicious Oatmeal Rhubarb Bars Recipe

Recipe by Toni Baldesera

0.0 from 0 votes

I’m excited to share my Rhubarb Oat Bars recipe, where tart rhubarb and wholesome oats meet a touch of cinnamon for a sweet and tangy treat worth saving and sharing.

Servings

servings

Calories

528

kcal

Equipment: 1. 8×8 inch baking pan, lined with parchment or greased so the bars lift out easy
2. Parchment paper, with an overhang for lifting
3. Medium saucepan for cooking the rhubarb
4. Large mixing bowl for the oat crust
5. Measuring cups and spoons, for accuracy
6. Sharp knife and cutting board to chop the rhubarb
7. Pastry cutter or food processor, or just use your fingers to cut in the butter
8. Wooden spoon or rubber spatula for stirring and spreading
9. Wire cooling rack so the bars cool completely
10. Oven mitts, safety first

Ingredients

1 lb fresh rhubarb about 3 cups
3/4 cup granulated sugar
2 tablespoons cornstarch
1 tablespoon lemon juice
1/2 teaspoon vanilla extract (optional)
1/2 teaspoon ground cinnamon
1 1/2 cups old fashioned rolled oats
1 1/2 cups all purpose flour
1 cup packed light brown sugar
1/4 cup granulated sugar
1/2 teaspoon fine salt
3/4 cup (12 tablespoons) cold unsalted butter cubed

Directions

Preheat oven to 350 F (175 C). Line an 8×8 inch pan with parchment leaving an overhang, or grease it well so bars can be lifted out later.
Trim and chop about 1 lb rhubarb into 1/2 inch pieces, you should have roughly 3 cups.
In a medium saucepan toss the rhubarb with 3/4 cup granulated sugar, 2 tablespoons cornstarch, 1 tablespoon lemon juice, 1/2 teaspoon vanilla extract (optional), and 1/2 teaspoon ground cinnamon. Let sit 5 to 10 minutes so the sugar draws out some juice.
Cook the rhubarb mixture over medium heat, stirring often, until it thickens and becomes glossy and bubbly, about 5 to 8 minutes. Taste and add a little extra sugar if it seems too tart. Remove from heat and let cool while you make the crust.
In a large bowl combine 1 1/2 cups old fashioned rolled oats, 1 1/2 cups all purpose flour, 1 cup packed light brown sugar, 1/4 cup granulated sugar, and 1/2 teaspoon fine salt. Sprinkle the 3/4 cup (12 tablespoons) cold unsalted butter cubes over the dry mix.
Use your fingers, a pastry cutter, or a food processor to cut the butter into the dry mix until it resembles coarse crumbs and holds together when pressed, about pea sized bits and some larger flakes. If it gets too warm chill for a few minutes.
Press about two thirds of the oat mixture firmly into the prepared pan to form an even bottom crust. Reserve the rest for the topping. You want a compact base so the bars slice cleanly.
Bake the crust alone for 12 to 15 minutes until it starts to set and the edges are lightly golden. This keeps the filling from making the crust soggy.
Spread the cooled rhubarb filling evenly over the hot crust, then sprinkle the remaining oat mixture over the top, gently pressing a bit so it sticks. Bake 25 to 30 minutes until the top is golden and the filling is bubbling at the edges.
Cool completely in the pan on a wire rack, at least 2 hours so the filling sets. Use the parchment to lift out and cut into bars. Store in the fridge up to 5 days or freeze for longer.

Notes

Below you’ll find my best estimate of this recipe’s nutrition facts. Treat the numbers as a guide rather than a rule—great food should nourish both body and spirit. Figures are approximate, and the website owner assumes no liability for any inaccuracies in this recipe.