Notable: I used my new vanilla powder in the topping -- vanilla extract is not suitable for dispersing into the dry ingredients, so this allows a slight flavor variation, meant to go with French Vanilla ice cream.
Using a fork and a sharp knife, I mixed/cut the topping ingredients together until the butter was in olive-sized pieces.
Then I filled up my baking dish with sliced apples and a few orphaned strawberries, sprinkled the fruit with lemon juice, and topped with the topping. I baked it for around 50 minutes at 375° -- after a bit of cooling, it thickened up nicely. My baking dish is an odd size, but this would work in a 9 by 9 inch pan.
For the topping, I used:
1 cup classic Quaker oats
1 cup brown sugar (compact)
1/3 cup flour
1 stick butter
1/2 tsp. vanilla powder
1/2 tsp. cinnamon
a handful of walnuts (around 1/2 cup)