Old-fashioned rhubarb crisp bars (vegan)

They’ve been in regular rotation in our family ever since.

The yellowed and well-worn recipe calls for ingredients like “oleo” and “nutmeats.” The instructions are slight and a little vague. So over time, the recipe has been modified and changed – first by my mom, and then by me.

While rhubarb is still in season, I knew I needed to share this easy updated recipe with you.

It’s made with top and bottom layers of sweet and chewy oatmeal crisp, dotted with crunchy pistachios. Then sandwiched between the layers is gooey, tart, and tangy rhubarb. There’s a dash of vanilla to make those dessert flavors pop.

Finally, the rhubarb crisp is cut into bars. They can be enjoyed on their own or alongside vanilla ice cream for a hot & cold treat.

Make a batch of rhubarb squares for your next potluck, cookout, family get-together, or holiday. (They’re perfect for spring and summer holidays like Memorial Day, Labor Day, and the Fourth of July.)

This dessert also freezes well in individual bars. Plan to pluck one out during winter months when you need a little taste of summer.

In this post:

Here are the ingredients you will need to make this recipe.

Rhubarb: Fresh is best, but you can also use frozen rhubarb for this recipe. If there’s any frost on your frozen rhubarb, quickly rinse it off before adding it to the pot while it’s still frozen.

(Need to know how to freeze rhubarb? Follow the directions in this easy Instagram reel.)

Sugar: The original recipe used both white and brown sugar. However, to keep things easy, I just use white sugar and then add molasses (which is what turns white sugar brown).

If you’d prefer, you can omit the molasses, and use white sugar in the rhubarb sauce and brown sugar in the oat crisp mixture. You’ll need one cup of each.

Cornstarch: Cornstarch thickens the rhubarb sauce, so that the bars aren’t runny. You want them to form into cohesive bars.

Vanilla: Use pure vanilla extract, not imitation vanilla.

Rolled oats: They’re also called old-fashioned oats. They can be replaced with quick oats, but do not use stoneground or steel cut oats. They won’t work in this recipe.

Flour: Choose all-purpose flour.

Molasses: This thick syrup is added to white sugar to make brown sugar. I use it in this recipe, so that two different types of sugar aren’t needed.

Baking soda: This is added to the oatmeal layer to help with browning and crisping.

Pistachios: Choose shelled and roasted pistachios. They can be salted or unsalted. If you’d prefer, replace them with an equal amount of your preferred chopped nuts. If you don’t like or can’t eat nuts, simply leave them out.

Non-dairy butter: Choose your preferred vegan butter. If you’d rather, it can be replaced entirely or in part with vegetable shortening.

This section shows how to make this recipe at a glance with process photos of the steps. For complete ingredient amounts & instructions, keep scrolling to the recipe card below.

1. In a pot, combine the following:

• Chopped rhubarb
• Sugar
• Cornstarch
• Water
• Vanilla extract

2. Stir frequently over a medium heat until thick like pie filling.

3. In a mixing bowl, combine the following:

• Rolled oats
• All-purpose flour
• Sugar
• Molasses
• Non-dairy butter
• Pistachios

Use a spoon and then your hands to make sure everything is evenly combined until there’s no dry flour left behind.

4. Pour about three-quarters of the oat mixture into a 9 x 13 baking dish. Lightly press it evenly across the dish.

Note: I use an ungreased glass baking dish. There’s enough non-dairy butter in the crisp that it comes out great. However, if you’d prefer to lightly oil your (metal or glass) baking dish, that’s fine too.

5. Gently pour the rhubarb mixture across the oats. Use a spoon to evenly spread it.

6. Scatter the remaining oat mixture across the top of the rhubarb.

7. Put the baking dish into the oven, and bake 30 minutes, until golden brown.

8. You can eat the rhubarb bars while warm. But for easier slicing, allow it to cool somewhat before cutting into squares.

You can make this recipe your own by varying the ingredients.

• Replace the cup of white sugar + molasses in the oats with a cup of brown sugar
• Replace pistachios with an equal amount of chopped walnuts, pecans, almonds, or cashews
• If you don’t like or can’t eat nuts, simply omit them
• Replace non-dairy butter in part or in full with vegetable shortening
• For an extra boost of flavor, add a dash of cinnamon to the oat topping

These rhubarb bars are terrific on their own as a sweet treat. I especially like them with a cup of hot coffee or English breakfast tea.

They’re also great alongside a scoop or two of non-dairy vanilla or mulberry ice cream.

To keep the oat topping crispy, wait until the bars have cooled before covering them.

The covered bars can be stored at room temperature on the counter for a day or two. After that, move them to the fridge. Over time, the crispy topping will start to soften. You can still enjoy them that way, or re-crisp them in the air fryer or oven.

Plan on eating the bars within about 3 or 4 days.

Rhubarb bars also freeze well. I like to wrap each bar individually in plastic wrap, and then put them all into a large freezer bag.

When you’re ready to eat them, you can pull out just as many bars as you need. Nosh on them right out of the freezer, or let them thaw in the refrigerator. Quickly warm them in the microwave, or re-crisp in the oven or air fryer.

Craving even more rhubarb? Make magic rhubarb pudding cake next! It’s another old-timey recipe that always delivers.

📖 Recipe

Old-fashioned rhubarb crisp bars (vegan)

Author: Cadry Nelson

5 from 4 votes

Don't know what to do with your rhubarb haul? Make these mouthwatering rhubarb crisp bars. Layers of oatmeal crisp are sandwiched around gooey rhubarb filling. Enjoy them warm, cold, or even frozen. Eat them on their own or alongside vanilla ice cream.

Print Pin Rate

Prep Time: 15 minutes minutes

Cook Time: 30 minutes minutes

Total Time: 45 minutes minutes

Servings: 20 people

Course: Dessert

Cuisine: American, Vegan

Keyword: old-fashioned, spring dessert, summer dessert

Ingredients

• ▢ 3 cups chopped rhubarb roughly ¾-inch pieces
• ▢ 2 cups sugar divided
• ▢ 2 Tablespoons cornstarch
• ▢ ¼ cup water
• ▢ 1 teaspoon vanilla extract
• ▢ 1 ½ cups rolled oats
• ▢ 1 ½ cups all-purpose flour
• ▢ 1 Tablespoon molasses
• ▢ ½ teaspoon baking soda
• ▢ 1 cup non-dairy butter
• ▢ ½ cup roasted pistachios

Instructions

• ▢
  Preheat oven to 375 degrees.
• ▢
  In a pot, combine rhubarb, 1 cup sugar, cornstarch, water, and vanilla over a medium heat. Stir frequently until a thick sauce forms around the rhubarb, about ten minutes. (If it starts to boil, lower the heat. If you're using frozen rhubarb, it may take a little longer.)

  Once the sauce has thickened, remove the pot from heat and set aside.
• ▢
  In a mixing bowl, combine rolled oats, all-purpose flour, molasses, baking soda, non-dairy butter, pistachios, and the remaining one cup of sugar. Start by using a spoon. Then use your hands to get everything evenly mixed and crumbly. When you're done mixing, there shouldn't be any dry flour left.
• ▢
  In a 9 x 13 baking dish, pour in about three-quarters of the oatmeal crisp mixture. Use your hands to lightly press it evenly across the bottom of the dish, making sure to get into all of the corners.
• ▢
  Gently pour the rhubarb mixture on top of the oatmeal crisp. Use a spoon to gently spread it evenly across to the edges.
• ▢
  Finish by sprinkling the remaining oatmeal crisp evenly across the top of the rhubarb mixture.
• ▢
  Put the baking dish into the oven, and bake uncovered for 30 minutes. (If it's not browned on top after 30 minutes, continue cooking for an additional 5 minutes or as long as necessary.)
• ▢
  Once the rhubarb crisp bars are browned on top, remove from the oven. You can enjoy it right away, but for easiest slicing, allow it to mostly cool first.
• ▢
  Cut into even-sized bars. Serve on its own, or alongside non-dairy vanilla ice cream.

Watch how to make it

Notes

The cup of sugar + molasses in the oatmeal crisp portion of the recipe can be replaced with 1 cup of brown sugar instead.

I use an ungreased glass baking dish, and it comes out great. However, if you’d prefer to lightly oil your (glass or metal) baking dish, that’s fine too.

Storage

Wait until the rhubarb crisp bars have cooled before covering them. The covered bars can be stored at room temperature on the counter for a day or two. After that, move them to the fridge. Be aware that the crispy topping will start to soften in the fridge. Plan on eating the bars within about 3 or 4 days.

They also freeze well. I like to wrap each bar individually in plastic wrap, and then put them all into a large freezer bag. When you’re ready to enjoy them, you can pull out just as many bars as you need. Eat them right out of the freezer, or let them thaw in the refrigerator. Quickly warm them in the microwave, or re-crisp in the oven or air fryer.

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Nutrition

Calories: 238kcal | Carbohydrates: 34g | Protein: 3g | Fat: 11g | Saturated Fat: 2g | Polyunsaturated Fat: 3g | Monounsaturated Fat: 5g | Trans Fat: 2g | Sodium: 99mg | Potassium: 133mg | Fiber: 2g | Sugar: 21g | Vitamin A: 31IU | Vitamin C: 2mg | Calcium: 26mg | Iron: 1mg