Original blost post: https://spatulagoddess.com/2011/07/10/rhubarb-apple-crumb-bars/

Time required: 2.5 hrs

Yields: 36 pieces

Tools required:

• baking pan: 10.5″ x 14.5″
• tinfoil
• mixer
• pastry blender

Crust ingredients:

1 C butter, softened (2 sticks)
⅔ C icing sugar
1 TSP pure vanilla extract
2½ C flour

Filling ingredients:

4 C rhubarb, washed and diced
4 C tart apples, peeled, cored, and diced
½ C granulated white sugar
3 TBSP powdered corn starch
2 TBSP water
Topping ingredients:

⅔ C quick-cooking oats, uncooked
½ C flour
⅓ C brown sugar, packed
¼ TSP cinnamon, ground
½ C butter, slightly softened (1 stick)

Instructions:

1. Pre-heat oven to 190.5°C / 375°F. Line baking pan with foil.
2. Prepare the fruit and set it aside.
3. Prepare crust: in mixer beat the butter, icing sugar and vanilla. Beat until light and fluffy. Add flour and mix until just combined.
4. Use hands to press dough into baking pan, bake 20 min.
5. Cool on rack 5 min.
6. Meanwhile prepare filling: in a large sauce pan, combine sugar, corn starch, and water.
7. Add fruit. Bring to a boil over Medium heat, reduce heat and simmer for 5 minutes. Stir often.
8. Meanwhile prepare topping: in a medium bowl stir: oats, flour, brown sugar, cinnamon. Cut in butter with pastry blender, and blend until you have coarse crumbs.
9. Spread fruit mixture evenly over crust.
10. Use hands to sprinkle topping over fruit.
11. Cover with tinfoil and pierce with fork. Bake 30 min.
12. Remove tin foil after 30 min, and lower temperature to 160°C / 320°F. Bake for an additional 25 min.
13. Cool completely in pan before slicing. When ready to serve, lift from pan, peel foil off the bottom. Slice lengthwise into 6 strips, then crosswise into 6 pieces.