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

In a mixing bowl, combine flour, sugar, cocoa powder, baking powder, baking soda, and salt.

Add milk, vegetable oil, eggs, and vanilla extract to the dry ingredients. Mix until smooth.

Pour the batter into the prepared cake pan and bake for 25 minutes or until a toothpick comes out clean.

Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.

Once the cake is cool, slice it in half horizontally to create two layers.

Spread half of the caramel sauce on the bottom layer and sprinkle with chopped peanuts.

Place the top layer on the bottom layer and repeat with the remaining caramel sauce and peanuts.

In a separate bowl, beat the softened butter until creamy. Gradually add powdered sugar and cocoa powder, alternating with milk, until smooth.

Spread the frosting over the top and sides of the cake.

Garnish with chopped peanuts and drizzle with additional caramel sauce.