1. Preheat the oven: Preheat your oven to 350°F (175°C). Grease and line the bottom of a 9-inch round cake pan with parchment paper.

2. Caramelize the strawberries: In a medium saucepan, melt the butter over medium heat. Stir in the brown sugar, vanilla extract, and cinnamon (if using), and cook for 2-3 minutes until the mixture is smooth and the sugar is dissolved. Add the sliced strawberries to the pan and cook for 3-4 minutes until they begin to soften and release some juice. Remove from heat and set aside.

Prepare the Cake:

3. Mix the dry ingredients: In a small bowl, whisk together the flour, baking powder, and salt. Set aside.

4. Cream the butter and sugar: In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy, about 3 minutes.

5. Add the eggs and vanilla: Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.

6. Add the dry ingredients and milk: Gradually add the dry ingredients in three additions, alternating with the milk, beginning and ending with the dry ingredients. Mix until just combined.

7. Assemble the cake: Pour the caramelized strawberry mixture into the prepared cake pan, spreading it evenly across the bottom. Carefully spoon the cake batter over the strawberries, spreading it out evenly with a spatula.

8. Bake the cake: Bake for 35–40 minutes, or until a toothpick inserted into the center of the cake comes out clean. The cake should be golden brown and spring back when lightly pressed.

9. Cool and invert: Allow the cake to cool in the pan for about 10 minutes. Run a knife around the edges to loosen it, then carefully invert the cake onto a serving plate. Remove the pan and parchment paper, and let the cake cool slightly before serving.

Serve:

10. Serve warm or at room temperature: Enjoy the cake on its own or with a dollop of whipped cream or vanilla ice cream for extra indulgence.