Preheat oven to 425F
In your Rectangular BounceBox, beat egg, milk, vanilla, and butter until well combined
Add flour, sugar, baking powder, and salt and mix until a smooth, thick batter forms
Fold in chopped fruit until evenly distributed
Bake on the center rack of your oven for 20 minutes
In the meantime, gently mix flour, brown sugar, and butter until just combined (take care not to overmix, you want lumps!)
After 20 minutes, lower the oven temp to 350F
Carefully remove the muffin from the oven and top generously with the crumble
Bake for another 20 minutes or until a toothpick comes out clean from the center
Allow to cool about 20 minutes
