Place the flour in a large bowl, add baking powder (I mix with a balloon whisk).
Add butter and rub into the flow lightly, using fingertips. Rub until it looks like breadcrumbs.
Add the sugar and combine until evenly mixed. Your topping is now ready.
Place the blackcurrants (fruit) into a deep dish, put the crumble on top. Bake at 350 degrees Farenheit for 30-40 minutes.