In a large mixing bowl, whisk flour, sugar, baking powder, and salt together.
Add butter slices to the flour mixture and cut into flour mixture using a pastry cutter.
Whisk buttermilk, egg yolk, and vanilla in a medium bowl until combined
Pour the wet ingredients into the dry ingredients, stir until combined.
Transfer the dough to the prepared skillet. Spread evenly.
Press sliced strawberries gently into the top of the dough.
Bake for 25-30 minutes or until golden brown or toothpick inserted comes out clean. Remove from the oven and let cool.