Spiced Brown Sugar Cake with Cinnamon Apple Filling and Maple Caramel German Buttercream

SPICED BROWN SUGAR CAKE

1. Preheat the oven to 350°f / 180°c. Grease three 6” cake pans, and line with parchment paper on the bottom.
2. In a medium bowl, whisk together the eggs, egg yolks, vanilla, milk, and sour cream.
3. In the bowl of a stand mixer fitted with the paddle attachment, combine the flour, sugar, brown sugar, baking powder, salt, cinnamon, nutmeg, ginger, allspice, and cloves. Mix briefly to combine.
4. With the mixer on low, add the butter a cube at a time, until fully incorporated and the mixture looks like sand.
5. Add half of the wet ingredients into the mixer. Mix until just combined, then add the second half of the wet ingredients. Mix on medium speed until just combined. Remove the bowl from the mixer and give a few folds with a rubber spatula to ensure that no dry ingredients remain.
6. Divide the batter between your three cake tins (I prefer to do this by weight - see notes). Bake for 25 to 30 minutes, or until the cakes are springy to the touch, and a skewer inserted into the middle comes out clean.
7. Remove from the oven and cool for 15 minutes in their pans, then turn onto a wire rack and allow to cool completely.

MAPLE CARAMEL

1. Place the maple syrup in a medium heavy bottomed saucepan. Place the heavy cream, corn syrup, vanilla, and salt in a small saucepan and heat over low heat just to warm.
2. Over medium heat, cook the maple syrup, stirring frequently with a whisk, until it registers 250°f / 121°c on a candy thermometer. Remove from the heat, and add the butter, whisking to combine, then add the heavy cream mixture, and whisk until incorporated. Transfer to a container and allow to cool, then place in the fridge and allow to cool completely.

SPICED APPLE FILLING

1. Place the chopped apples, brown sugar, cinnamon, salt, and vanilla into a medium heavy bottomed saucepan. Cook over medium heat, stirring often, until the apples are tender, approximately 10-12 minutes. Do not worry if it looks dry to begin with - the apples will release some of their moisture as they start to cook down.
2. Transfer to a container and allow to cool completely. Store in the fridge.

MAPLE GERMAN BUTTERCREAM

1. In a bowl, whisk together the maple syrup, egg, egg yolk, corn starch, and salt. In a medium saucepan, heat heavy cream, milk, and vanilla to just shy of a simmer. Remove from the heat.
2. Using one hand to whisk constantly, pour half of the hot milk mixture into the egg mixture. This helps to temper the eggs and stop them from scrambling. Whisk until incorporated, and then pour the whole lot back into the saucepan.
3. Heat the milk and egg mixture over medium heat, whisking constantly, until it begins to bubble. It will thicken quickly. Once it has thickened, cook for one minute, then remove from the heat. Pour into a shallow container or bowl of a stand mixer and press some plastic wrap over the surface to avoid a skin from forming. Refrigerate until cold - at least four hours, preferably overnight. If you need to speed this process up, you can place the pastry cream in a bowl, then place the bowl in an ice bath. Stir frequently.
4. Fit your mixer with the whisk attachment, and place the pastry cream in the bowl. Whip the mixture on medium until creamy and lump-free. Begin adding the butter, a few cubes at a time, until fully incorporated. It may look curdled at some point but just keep whipping - it will come together! Once all of the butter has been added and the mixture is homogenous, add in the caramel and whip on high speed until incorporated. Switch to the paddle attachment and mix on low for 2-3 minutes to help remove any air bubbles.

ASSEMBLY

1. Level off the cake layers. Transfer some of the buttercream to a piping bag fitted with a medium round tip - this will be used to make a buttercream dam to hold in the spiced apple filling.
2. Secure one of the layers of cake to a cake turntable or cake stand using a little buttercream. Add about ⅓ cup of buttercream onto the first layer of cake, and smooth using an offset spatula. Create a buttercream dam using the buttercream in the piping bag by piping a ring of frosting around the outside edge of the first layer. Fill in the ring with spiced apple filling - strain the filling with your spoon, leaving the liquid behind. Place the second layer of cake onto the first, pressing very lightly to secure, and sealing the joins with a thin layer of buttercream. Repeat the layering process - add a ⅓ cup of buttercream, make a dam, fill with apple filling, then top with the third layer of cake - I like to put this one upside down to ensure that the top of the cake is flat. Return the rest of the buttercream in the piping bag to the bowl with the buttercream.
3. Coat the outside of the cake with a layer of buttercream using an offset spatula, then, using a cake scraper, smooth off the sides, exposing some of the cake for a semi naked finish, or covering the whole cake for a more solid finish (if you do this, I recommend crumb coating the cake, chilling briefly, then adding on another layer of buttercream). Smooth off the top edge of the cake using an offset spatula, wiping between strokes.
4. Add a caramel drip to the top edge of the cake if desired (see notes about caramel consistency). Transfer some of the remaining buttercream into a piping bag fitted with a French star tip such as an ateco #865. Pipe blobs of buttercream on the top of the cake.
5. Chill the cake until ready to serve. Remove from the fridge about an hour before serving to bring to room temperature.
6. Store leftovers in an airtight container in the fridge.