Old-Fashioned custard rhubarb bars, with a shortbread base and a rhubarb custard topping. A classic rhubarb recipe and a great use for fresh or frozen rhubarb.

rhubarb bars cut on serving board

These custard rhubarb bars are always on my baking list during rhubarb season. They can be made with fresh or frozen rhubarb, too!

Why you’ll love these custard rhubarb bars

  • These old-fashioned rhubarb bars are the perfect meeting of sweet and sour.
  • The rhubarb sits in a lovely custard base, all on top of a shortbread base.
  • These rhubarb bars can be made with either fresh or frozen rhubarb.

Ingredients and substitutions

Rhubarb – you can use either fresh or frozen rhubarb for these bars. If frozen, use from frozen and allow for a bit of extra baking time.

How to make custard rhubarb bars

  1. Combine the ingredients for the shortbread base in a bowl.
  2. Cut the butter into the dry ingredients until crumbly.
  3. Press the shortbread base into a parchment-lined 8×8-inch baking pan and bake for 10 minutes.
  4. Meanwhile, combine the ingredients for the topping in a bowl and stir together with a fork.
  5. Add the diced rhubarb to the bowl and stir in.
  6. Remove the base from the oven and pour the topping over top. Return to the oven and bake a further 35-40 minutes or until set and golden.
old-fashioned rhubarb bars on serving board

Making ahead, storing and freezing

I like to store these bars in an air-tight container in the refrigerator, where they keep well for up to 5 days.

These will also freeze well for up to 2 months.

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rhubarb bars cut on serving board

Get the Recipe: Old-Fashioned Custard Rhubarb Bars

Classic, old-fashioned custard rhubarb bars, with a shortbread base and a rhubarb custard topping. These can be made with fresh or frozen rhubarb.
5 stars from 1 rating
Prep Time: 15 minutes
Cook Time: 45 minutes
Total Time: 1 hour
Yield: 16 servings

Ingredients

For the base:

  • 3/4 cup all-purpose flour, spooned and levelled
  • 6 Tablespoons butter, cold and cut into 6 pieces
  • 3 1/2 Tablespoons icing/confectioners' sugar

For the topping:

  • 1 1/2 large eggs, very lightly beaten *see Note 1 below
  • 3 Tablespoons all-purpose flour
  • 1 cup + 2 Tablespoons granulated white sugar
  • 1 1/4 cups rhubarb, finely chopped, fresh or frozen

Instructions
 

  • Preheat oven to 350F (regular bake setting/not fan-assisted).
  • Spray an 8×8 baking pan with baking spray and line with parchment paper. Set aside.
  • Make base by combining the base ingredients in a medium bowl. Using your fingertips or a pastry cutter, cut the cold butter into the dry ingredients until you have a crumbly mixture with pea-sized pieces of butter. Press the mixture into the bottom of the prepared pan. Bake in preheated oven for 10 minutes.
  • Meanwhile, add the eggs to a medium bowl and stir gently with a fork. Add the flour and sugar and stir together with a fork. Add the rhubarb and stir to combine.
  • When the base has pre-baked, remove it from the oven and pour filling over top. Use a spoon to spread out evenly over the base.
  • Return the pan to the oven and bake a further 35-40 minutes, until lightly golden and the tip of a butter knife inserted in the centre comes out clean. (Frozen rhubarb will take a few minutes extra baking generally).
  • Remove from oven and allow to cool completely in the pan before slicing into squares. Garnish with icing/confectioners' sugar, if desired.
  • (I like to store these in the refrigerator. You can also freeze up to 2 months).

Notes

Note 1: To get 1/2 an egg, break an egg into a small bowl, stir together with a fork and use just 1/2 of it (you can eyeball it).
You can double the recipe (use the “2X” button) and bake in a 9×13-inch pan.
Be sure to read the notes above this Recipe Card, for more tips on making this recipe, as well as step-by-step photos that you might find useful. 
Cuisine: American, Canadian
Course: Dessert
Serving: 1serving, Calories: 144kcal, Carbohydrates: 24g, Protein: 1g, Fat: 5g, Saturated Fat: 3g, Polyunsaturated Fat: 0.3g, Monounsaturated Fat: 1g, Trans Fat: 0.2g, Cholesterol: 29mg, Sodium: 41mg, Potassium: 43mg, Fiber: 0.4g, Sugar: 18g, Vitamin A: 166IU, Vitamin C: 1mg, Calcium: 13mg, Iron: 0.5mg
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