In Grandmother's day, rhubarb was considered a "spring tonic". Although it's technically a vegetable, it is usually served as a fruit. At our house, we used the first rhubarb of the season to make this rhubarb custard pie, and later in summer, we'd make a delicious drink with it, cooked, blended and mixed with strawberry punch.
Preheat oven to 425°. In a small bowl, lightly beat eggs; blend in milk. Combine sugar and tapioca; stir into egg mixture. Let stand for 15 minutes.
Meanwhile, on a lightly floured surface, roll one half of dough to a 1/8-in.-thick circle; transfer to a 9-in. pie plate. Trim even with rim. Add rhubarb to crust. Pour egg mixture over rhubarb. Dot with butter.
Roll remaining dough to a 1/8-in.-thick circle. Place over filling. Trim, seal and flute edge. Cut slits in top. If desired, brush top crust with cream.
Bake for 15 minutes. Reduce oven setting to 350°. Bake until lightly brown, 35-40 minutes longer. If desired, sprinkle with cinnamon-sugar. Cool on a wire rack for 1 hour. Refrigerate for at least 3 hours before serving. Refrigerate leftovers.
Rhubarb Custard Pie Tips
How can you avoid making a runny rhubarb custard pie?
Rhubarb naturally contains a lot of water, and is often cooked beforehand or combined with tapioca in baking. In this pie, we accommodate for any extra liquid by using quick-cooking tapioca. The tapioca will absorb most of the liquid, so there shouldn't be any concerns over runny rhubarb custard pie!
Should you thaw frozen rhubarb before using it in rhubarb custard pie?
Yes, it's a best practice to thaw frozen rhubarb before using. Thaw in the refrigerator or at room temperature, draining any excess liquid before using it in rhubarb dessert recipes.
How do you store rhubarb custard pie?
Store it for up to 4 days, covered in the refrigerator. Freezing delicate custard pies like this one isn't the best choice, because they can start to weep excess liquid, and the crust could become soggy. Check out our guide on how to freeze a pie for more tips.