Preheat over to 375°F and line a muffin pan with liners and set aside.
Cream together the butter and sugar in a large mixing bowl.
Beat in egg and vanilla. The mixture will be a bit lumpy, that's okay.
In a separate, large bowl, whisk together the flour, baking powder, and salt.
Slowly add buttermilk and flour mix, alternating between each, until incorporated into the butter mix. Beating until completely combined.
Gently fold in about half OR ALL of the strawberries. See notes.
Add about 1/4 cup of batter to each muffin liner then load up the tops of the muffins with the remaining strawberries.
In a mixing bowl, beat the crumble ingredients until pea-sized crumbs form then sprinkle crumble on the tops of the muffins.
Reduce oven heat to 350°F and bake muffins for 18 to 20 minutes.