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

Sift together the all-purpose flour, granulated sugar, unsweetened cocoa powder, baking powder, baking soda, and fine salt in a mixing bowl.

In a separate bowl, whisk together the water (or brewed coffee), buttermilk, vegetable oil, eggs, and vanilla extract until smooth.

Slowly pour the wet mixture into the dry ingredients and gently fold together until just combined.

Divide the batter among the prepared pans and bake for 22-25 minutes, or until a toothpick comes out clean. Cool in pans for 10 minutes before transferring to a wire rack.

To make the peanut caramel, heat granulated sugar in a saucepan until melted and amber in color, then whisk in butter, heavy cream, and a pinch of salt.

For the peanut butter frosting, beat together butter and peanut butter until fluffy, gradually adding vanilla extract and powdered sugar until smooth.

Assemble the cake by stacking the layers with peanut butter frosting and drizzling with peanut caramel in between.

For ganache, heat heavy cream until simmering, then pour over chocolate chips and stir until smooth.

Pour ganache over the assembled cake, allowing it to drip down the sides, and top with remaining peanut caramel and chopped Snickers bars.