about 4-5 cups of frozen berries (I always have a blueberry/blackberry/raspberry mix in my freezer for smoothies and baking, and I just filled my pie dish with those)
1 tablespoon caster sugar
1 tablespoon corn starch/corn flour
1 cup plain flour
1½ cups rolled oats
½ cup firmly packed brown sugar
4 tablespoons of butter, cubed
a splash of olive oil
Instructions
Preheat your oven to 375 F/ 190 C
Fill your pie dish with frozen berries, then sprinkle the spoonfuls of sugar and corn starch/flour over the top. Mix to combine.
Make the crumble: in a medium bowl, mix flour, oats, sugar, and butter. Using a rubbing motion between your thumbs and index and middle fingers (like the "money" gesture, only in pastry), rub the butter into the other ingredients until you have pea-sized crumbles of oats and floury butter. If your crumble needs a bit of help forming crumbles, add a splash of olive oil.
Spread the crumbles over the top of the berries and bake in the middle of the oven for about 30 minutes.
This might sound strange, but this crumble is better after it has a chance to cool and settle into itself.
Recipe by The Bright Kitchen at https://www.thebrightkitchen.com/summer-berry-crumble/