1-Bake the Chocolate Cake Layers: Preheat oven to 350°F, line four 8-inch pans with parchment. Sift dry ingredients (flour, sugar, cocoa, baking powder, baking soda, salt), whisk wet ingredients (water, buttermilk, oil, eggs, vanilla), combine, divide batter evenly. Bake 22-25 minutes until a toothpick comes out with moist crumbs. Cool in pans 10 minutes, then freeze 30 minutes before leveling.

2-Make the Peanut Caramel: Make a dry caramel: melt sugar in a saucepan over medium heat, adding a quarter cup at a time and stirring until fully dissolved and amber. Remove from heat, stir in butter, heavy cream, and salt. Cool, then whip with a mixer until light and thick. Reserve 1/3 cup for drips; fold 3/4 cup chopped salted peanuts into the remainder.

3-Make the Peanut Butter Buttercream Frosting: Beat room-temperature butter and creamy peanut butter until smooth. Add vanilla and salt, then gradually beat in powdered sugar and heavy cream until fluffy. Adjust consistency with extra cream or sugar if needed.

4-Stack and Fill the Cake Layers: Place first layer on a cake board with a dab of buttercream. Spread a layer of buttercream, pipe a dam around the edge, and fill the center with one-third of the peanut caramel. Repeat with next two layers. Flip the top layer upside down for a flat surface.

5-Chill and Frost the Cake: Freeze the stacked cake for 5-10 minutes to set. Frost the entire cake with the remaining buttercream, smoothing it with a bench scraper. Chill again for 30 minutes in the fridge or 10 minutes in the freezer until firm.

6-Make the Chocolate Ganache: Heat heavy cream in the microwave until bubbling, then pour over milk chocolate chips. Let sit 1 minute, stir until smooth. Adjust thickness with more cream or chips if necessary.

7-Decorate the Snickers Cake: Drizzle the reserved caramel over the edge (warm slightly if too thick). Pour ganache on top and gently push over the edge with an offset spatula. Press chopped peanuts around the base, add a ring of chopped mini Snickers bars on top, and sprinkle with flaky sea salt.