Preheat your oven to 350°F (175°C). Line four 8-inch round cake pans with parchment paper and grease the sides.

In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, cocoa powder, baking powder, baking soda, and fine salt.

In another bowl, whisk together the warm water, buttermilk, vegetable oil, eggs, and vanilla extract until smooth.

Pour the wet mixture into the dry ingredients and mix gently until just combined.

Divide the batter evenly across the prepared pans and bake for 22-25 minutes.

Remove the cakes and cool in the pans for about 10 minutes before transferring to a wire rack.

For the peanut caramel, heat granulated sugar in a medium saucepan until melted and amber-colored. Mix in butter, cream, and salt.

Once cooled, whip the caramel until light and thick, then fold in chopped salted peanuts.

To prepare the frosting, beat butter and peanut butter until smooth, then add vanilla, salt, powdered sugar, and cream.

Layer the cake by spreading frosting and caramel between each layer, then chill if necessary.

To make ganache, heat cream until simmering, pour over chocolate chips, and stir until smooth.

Pour ganache over the top of the assembled cake, allowing it to drip down the sides, then decorate with caramel and crushed peanuts.