Place the chopped rhubarb and strawberries in a bowl, sprinkle with sugar, cornstarch, and almond extract.
Stir to combine, and let sit while you make the topping.
Cut the stick of butter up into tablespoon size pieces or smaller.
Put the flour, butter, pecans, oats, salt, cinnamon, and brown sugar into a bowl. Use a pastry blender or your hands to thoroughly mix everything together.
Spread the rhubarb mixture evenly in a greased 9 x 13 baking dish.
Sprinkle the topping over the rhubarb mixture so it is evenly distributed.
Bake for 35-40 minutes. The filling will be bubbling at the edges and the topping should be golden brown.
Serve warm with ice cream or whipped cream.
You can use all rhubarb instead of a mixture of rhubarb and strawberries. If you do, you may want to add a little bit more sugar as rhubarb is more tart.This dessert can be made with fresh or frozen fruit. If you use frozen fruit, you may need to increase your bake time slightly.