Preheat your oven to 350°F (175°C) and grease a 9-inch round cake pan with unsalted butter. Optionally, line the bottom with parchment paper.

Melt 6 tablespoons of unsalted butter in a medium saucepan over medium heat. Stir in 1 cup of brown sugar and cook for about 2 minutes until bubbly. Mix in 1 tablespoon of optional maple syrup, then pour into the prepared cake pan and sprinkle 1 cup of chopped pecans on top.

In a large mixing bowl, whisk together 1.5 cups of all-purpose flour, 2 teaspoons of baking powder, and 0.5 teaspoon of salt.

In another bowl, beat 2 large eggs and 1 cup of granulated sugar using an electric mixer until pale and fluffy. Gradually add 1 cup of milk (or buttermilk), 1 teaspoon of vanilla extract, and 6 tablespoons of melted unsalted butter, mixing until combined.

Gently fold the dry ingredients into the wet mixture using a spatula until just combined.

Pour the batter over the caramel and pecan layer in the prepared pan and smooth the top.

Bake for 35–40 minutes, or until golden brown and a toothpick inserted in the center comes out clean.

Let the cake cool in the pan for 10–15 minutes, then carefully invert onto a serving plate.