Preheat the oven to 350°F (175°C). Grease a 9-inch round cake pan and set aside.

To make the topping, melt ½ cup butter in a small saucepan over medium heat. Stir in the brown sugar and cook until the sugar dissolves and the mixture becomes smooth, about 2 minutes. Remove from heat and stir in the vanilla extract.

Pour the caramelized butter-sugar mixture into the prepared cake pan, spreading it evenly. Arrange the sliced strawberries over the caramel mixture in a circular pattern.

For the cake batter, whisk together the flour, baking powder, baking soda, and salt in a medium bowl.

In a large bowl, cream together the softened butter and granulated sugar until light and fluffy, about 3 minutes. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.

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

Pour the cake batter over the strawberries in the cake pan and spread evenly.

Bake in the preheated oven for 35-40 minutes, or until a toothpick inserted into the center comes out clean.

Let the cake cool in the pan for about 5 minutes, then run a knife around the edges to loosen. Invert the cake onto a serving plate and carefully remove the pan.

Serve warm or at room temperature. Optionally, top with whipped cream or vanilla ice cream.