Preheat your oven to 350°F (175°C) and line a 9x13-inch baking pan with parchment paper, greasing it lightly.

Cream together unsalted butter and granulated sugar until light and fluffy. Add eggs and vanilla extract until smooth.

Whisk together all-purpose flour, baking powder, and salt in a separate bowl. Gradually mix with the butter mixture to form a thick dough.

Spread two-thirds of the batter evenly in the baking pan to create the base.

Toss chopped strawberries with cornstarch and optional sugar. Layer over the batter in the pan.

Drop dollops of the remaining batter over the strawberries, allowing some fruit to peek through.

Bake for 30 to 35 minutes until golden brown. Cool in the pan for 10 minutes before transferring to a wire rack.

Slice into squares and serve with whipped cream or powdered sugar if desired.