Preheat the oven to 350F/177C. Prepare three, 8-inch (20-cm) round cake pans: grease the sides and line the bottoms with parchment paper.
Prepare the cake layers first. In a large mixing bowl, combine the melted butter, dulce de leche and vanilla extract. Using a mixer, mix the ingredients on medium speed until the butter and caramel are well combined. Add the eggs and mix again until smooth. Add the milk last and mix again.
In a separate bowl, combine the dry ingredients: sifted flour, baking powder, salt and the finely chopped almonds. Add the dry ingredients to the batter and mix just until the flour is incorporated, about 1 minute.
Divide the cake batter evenly between the three prepared pans. Bake in the preheated oven for 28 to 30 minutes, until a toothpick inserted into the center comes out clean. When cake layers are done, cool them completely on a wire rack. Once cooled, use a long serrated knife to level the tops.
For Caramel Buttercream:
Place softened, unsalted butter into mixing bowl. Whisk on high speed for about 5 minutes, until butter is light and fluffy. Scrape down sides of mixing bowl often to get all the butter mixed well. Add the dulce de leche (cooked sweetened condensed milk). If you cannot find dulce de leche, use a similar caramel sauce. If necessary, increase the amount of confectioner's sugar to thicken the frosting.
Add the vanilla and salt. Start by adding 1/4 teaspoon salt, then add more if needed. Begin adding the confectioner's sugar 1 cup at a time, scraping down sides of mixing bowl often to get everything incorporated. Make sure to sift confectioner's sugar before adding to avoid any clumps. After adding all sugar, whisk on high speed for 2 to 3 minutes to get frosting very fluffy.
To assemble the cake, first pour several tablespoons of store-bought chocolate sauce (can also use chocolate ganache) over each cake layer and allow it to sink into the cake. Frost each layer with a generous amount of frosting and top with a generous amount of crushed almond roca candy pieces. Frost the top and sides of the cake, smoothing the frosting down with a flat spatula.
Garnish the sides of the cake with any remaining crushed candy pieces and diced almonds. Refrigerate the cake for 30 minutes before garnishing with chocolate ganache, frosting dollops and candy pieces. I used Ateco tip #4FT for the dollops.
Prepare the chocolate ganache: combine the chocolate, cream and a touch of shortening in a large measuring cup. Heat the mixture in the microwave in 30 second intervals, stirring until the chocolate is melted and smooth. Allow the mixture to cool slightly, then pour over the top of the cake, nudging the chocolate down the sides of the cake using a flat spatula.
For White Chocolate Garnish: cut 6 squares of acetate paper or parchment paper. Melt the chocolate melts in the microwave until smooth, then transfer into a disposable pastry bag or ziplock bag. Pipe the chocolate in criss-cross pattern onto the prepared squares. Allow the chocolate to sit for a few minutes, then transfer the squares into tall glasses, shaping the chocolate into a scallop. Allow the chocolate to set completely, then gently peel from the acetate and place onto the cake.