Preheat the oven to 350 F. Butter two 8 inch round cake pans, sprinkle with flour and line with parchment rounds. Set aside.
In a large bowl combine all the dry ingredients (flour, sugar, cocoa powder, baking powder, soda and salt.) Whisk together until well combined.
Add all the rest of the ingredients- (eggs, buttermilk, warm water, oil and vanilla,) and whisk until smooth, clump-free and glossy. (Don't over-mix)
Divide the batter evenly among the pans, and bake for 30-40 minutes, (depending on your oven,) or until a cake tester inserted into the center comes out clean. Cool completely before frosting.
Cream butter and powdered sugar until smooth, creamy and well combined. Gradually add the crushed chips/pretzels. Add a splash of milk if frosting feels too thick/stiff. Beat on high until smooth.
Use a serrated knife to level and torte the cake. Slice each layer evenly into two additional layers.
Place one layer on a turntable or cake stand. Spread 1/4 of the caramel sauce over the first cake layer. Top with 1/4 of the frosting.
Add another cake layer and repeat, spreading the caramel sauce and then frosting.
When you get to the top layer, spread on the remaining frosting and drizzle with caramel sauce. Garnish with crushed chips and pretzels.
* You want the caramel to be thick and spreadable, so let it firm up after making. Either make your caramel in advance or pop it in the freezer until it is firm and spreadable. You can then warm the remaining sauce before drizzling it over the top of the cake.
Chocolate Cake Recipe adapted from: Martha Stewart