Preheat the oven to 350°F and grease a muffin tin.

Cream the butter and sugar together until light and fluffy, then mix in the egg and vanilla.

Stir in the flour, baking powder, and salt until a soft dough forms.

Gently fold in the white chocolate chips and diced strawberries.

Press the dough evenly into the muffin tin wells, forming small cups.

Bake for 12 to 15 minutes, until lightly golden on the edges.

While still warm, press down the centers gently if needed, then let cool before removing.