The Ultimate Chocolate Hazelnut Cake Recipe

Chocolate Hazelnut Cake
0 Start by preheating your oven to 350°F. Prepare three 6-inch cake pans by lining the bottoms with parchment paper and lightly spraying the sides with baking spray. Dust with flour to prevent sticking, especially near the sides of your cake pan. Set aside.
2 Sift your dry ingredients: all-purpose flour, hazelnut meal, cocoa powder, baking powder, baking soda, and salt into a large mixing bowl. This ensures an even cake rise and avoids dry cake spots.
3 Using a stand mixer with the paddle attachment (or a large bowl and an electric mixer), beat the oil and sugar together on medium speed for about a minute. 
4 Add eggs one at a time, fully mixing between each addition. Add the vanilla extract and sour cream, and mix until just combined.
5 Alternate adding the dry ingredients and hot coffee to the wet mixture, starting and ending with the dry. Scrape the bottom of the bowl with a rubber spatula to ensure everything’s mixed evenly. Don’t overbeat—mix until just combined.
6 Evenly divide your cake batter into the prepared pans. Bake two cakes at a time if needed to avoid uneven baking. Bake for 45–60 minutes or until a toothpick comes out clean from the center.
7 Let the cakes cool in their pans for 10 minutes, then remove them from the cake pans and transfer them to a wire rack to cool completely. While they cool, start on the frosting.
Chocolate Hazelnut Frosting
9 Beat the unsalted butter with the whisk attachment until it’s light and creamy, about 1 minute. Add the hazelnut spread and mix until smooth.
10 Sift in the powdered sugar and cocoa powder slowly to avoid a sugar cloud. Mix on low, then increase the speed until your frosting is fluffy and well-blended.
11 Add the vanilla and salt, then beat for another 1–2 minutes. If needed, add a splash of milk to loosen the consistency slightly if needed.
Assemble
13 Once your cakes are completely cool, trim the top of the cake layers if needed to make them flat and even. Place the first cake layer onto a serving plate or cake board, securing it with a small dab of frosting underneath.
14 Spread a third of the chocolate hazelnut spread on top of the cake. Sprinkle 1/3 cup chopped hazelnuts evenly over the spread, then press them gently into place. Add a thin layer of frosting over the hazelnuts to help the second layer stick.
15 Place the second layer and repeat. After placing the third layer, press gently to settle the entire cake.
16 Apply a crumb coat—a thin layer of frosting around the whole cake to trap crumbs. Chill the cake for 15–20 minutes to set it.
17 Add an extra layer of frosting on top of the crumb coat.
18 To finish, press chopped hazelnuts into the sides of the cake by hand. Hold the cake over a tray to catch the extras. Sprinkle more hazelnuts over the top of the cake, lightly pressing them in so they stay in place. Use an offset spatula to smooth the top and tidy the edges.