Preheat over to 375 F.
Line muffin pan with liners.
Cream butter and sugar in a mixing bowl. Beat in egg and vanilla, mixture will be a bit lumpy, that's okay.Combine flour, baking powder, and salt in a separate bowl. Slowly add Milk and flour mix, alternating between until incorporated in the butter mix. Beat until completely combined. Gently fold in about half the strawberries. Add about 2 tbsp of batter to each muffin liner.
Load up the tops of the muffins with remaining strawberries. In a mixing bowl, beat crumble ingredients until it looks like, well... a crumble.
Sprinkle crumble over the strawberries.
Reduce oven heat to 350 F.
Bake muffins for 18-20 minutes.