Arrange strawberry slices in a single layer over the sugar, overlapping slightly to cover the bottom of the pan.

In a large bowl, beat softened butter and sugar together until light and fluffy, about 3 minutes.

Add eggs one at a time, beating well after each addition. Mix in vanilla, strawberry extract if using, and lemon zest.

In a separate bowl, whisk together flour, baking powder, and salt.

Add the flour mixture to the butter mixture in two additions, alternating with the milk and sour cream, beginning and ending with flour. Mix until just combined.

Spread the batter evenly over the strawberry layer.

Bake for 40 to 45 minutes, until the center springs back lightly when touched and a toothpick inserted in the center comes out clean or with a few moist crumbs.

Cool in the pan for 10 minutes, then run a knife around the edge and invert onto a serving plate. Serve warm or at room temperature.