Preheat the oven to 180°C. Grease and flour two 20 cm round cake pans.

In a large bowl, mix 200 grams of all-purpose flour, 1 teaspoon of baking powder, and a pinch of salt. Set aside.

In another bowl, cream together 200 grams of unsalted butter and 200 grams of granulated sugar until light and fluffy. Add 4 eggs, one at a time, mixing well after each addition. Stir in 1 teaspoon of vanilla extract.

Gradually add the dry ingredients to the wet ingredients, alternating with 100 ml of milk, beginning and ending with the dry ingredients. Mix until just combined.

Divide the batter evenly between the prepared cake pans. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Allow the cakes to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

To prepare the caramel frosting, melt 100 grams of unsalted butter in a saucepan over medium heat. Add 200 grams of brown sugar and 50 ml of milk, stirring constantly until the sugar dissolves. Bring the mixture to a boil and cook for 2 minutes. Remove from heat and let it cool slightly.

Gradually add 200 grams of powdered sugar to the caramel mixture, whisking until smooth and creamy. If the frosting is too thick, add a little more milk to achieve the desired consistency.

Place one cake layer on a serving plate and spread a generous amount of caramel frosting on top. Place the second cake layer on top and cover the entire cake with the remaining frosting. Decorate with chopped nuts or caramel drizzle, if desired.