Every bite of this impressive layer cake is infused with the flavor of speculoos cookie butter, that delicious concoction made from cinnamon-spiced Biscoff cookies. The cake itself is my basic go-to vanilla layer cake, which I soak with a cinnamon- and orange-infused syrup. After the soaking, I spread the layers first with cookie butter, then a generous layer of speculoos cookie butter buttercream. The sides are coated with a combination of cake crumbs and crunchy speculoos cookie crumbs. Despite its grand appearance, there’s nothing difficult about this cake, but it does take some time, so save it for a special occasion (or person). P.S.: I’ve given instructions to make either a 6-inch or 9-inch cake, so you can make the one you prefer.

Thank you for reading this post, don't forget to subscribe!

Ingredients

Vanilla Layer Cake (for a 6-inch cake):

2 1/4 cups (256 grams) cake flour
1 ¾ teaspoons baking powder
1/4 teaspoon plus 1/16 teaspoon salt
12 tablespoons (170 grams) unsalted butter, softened
1 ¼ cups (250 grams) granulated sugar
3 large (150 grams) eggs
1 teaspoon vanilla paste or extract
3/4 cup (181 grams) whole milk

Vanilla Layer Cake (for a 9-inch cake):

3 cups (341 grams) cake flour
2 1/2 teaspoons baking powder
1/2 teaspoon salt
16 tablespoons (227 grams) unsalted butter, softened
1 3/4 cups (350 grams) granulated sugar
4 large eggs
1 ½ teaspoons vanilla paste or extract
1 cup (242 grams) whole milk

Spiced Soaking Syrup:

2/3 cup (157 grams) water
1/2 cup (100 g) granulated sugar
1 cinnamon stick
1 strip orange peel (bitter white part removed)

Speculoos Cookie Butter Buttercream (for a 6-inch cake):

4 large (120 grams) egg whites
¾ cup (150 g grams) granulated sugar
2 tablespoons (30 grams) water
24 tablespoons (340 grams) unsalted butter, softened but cool
3/4 teaspoon vanilla paste or extract
1/3 cup (80 grams) speculoos cookie butter (such as Biscoff brand)

Speculoos Cookie Butter Buttercream (for a 9-inch cake):

5 large (150 grams) egg whites
1 cup (200 grams) granulated sugar
2 tablespoons (30 grams) water
30 tablespoons (423 grams) unsalted butter, softened but cool
1 teaspoon vanilla paste or extract
1/2 cup (120 grams) speculoos cookie butter (such as Biscoff brand)

Assembly:

14 Biscoff speculoos cookies (108 grams)
1/3 cup (80 grams) to ½ cup (120 grams) cookie butter

Instructions

Make the cakes:

Position a rack in the center of the oven and preheat the oven to 350° Grease the bottom and sides of either two round 6-inch diameter by 3-inch high cake pans (to make a 6-inch cake) OR two round 9-inch diameter by 2-inch high cake pans (to make a 9-inch cake). Dust the pans with flour and tap out the excess.

In a medium bowl, sift together the cake flour, baking powder, and salt. Whisk to combine and set aside.

In the bowl of an electric mixer, using the paddle attachment, beat the butter at medium speed until creamy, about 30 seconds. Gradually add the sugar and beat at high speed for 3 minutes, until well blended and light. Scrape down the sides of the bowl with a rubber spatula, reduce the speed to medium, and add the eggs one at a time, beating well after each addition and mixing until blended. Beat in the vanilla. Reduce the speed to low and add the flour mixture in three additions, alternating it with the milk in two additions. Mix just until blended. Scrape the batter into the prepared pans, dividing it evenly, and smooth the tops with a rubber spatula.

Bake the cakes for 20 to 25 minutes (for the 9-inch cakes) OR 40 to 45 minutes (for the 6-inch cakes), until they are lightly golden brown on top and a toothpick inserted into the center of each cake comes out clean. Cool the cakes in the pans, set on wire racks, for 15 minutes.

Invert the cakes onto wire racks, reinvert them so that the domed side is up, and cool completely.

Make the Spiced Soaking Syrup:

In a small saucepan, combine the water, sugar, cinnamon stick and orange peel and bring to a boil over medium-high heat, stirring occasionally just to dissolve the sugar. Remove the pan from the heat and let stand at room temperature until ready to use (if you make this the day before you assemble the cake, cover and refrigerate the syrup).

Make the Cookie Butter Buttercream:

Pour enough water into a skillet so that it comes 1/2-inch up its sides. Bring the water to a simmer; reduce the heat to medium-low to maintain a simmer.

In the bowl of an electric mixer, combine the sugar, egg whites, and water. Place the bowl in the skillet of water and whisk gently until the mixture registers 160°F on an instant-read thermometer.

Transfer the bowl to the mixer stand and, using the whisk attachment, beat at medium-high speed until the meringue is cool and forms stiff, shiny peaks, about 4 minutes.

Reduce the speed to medium and beat in the butter, one tablespoon at a time. Beat in the vanilla paste and cookie butter. Beat at high speed until the buttercream is smooth, about 1 minute. Set aside about 1/2 cup (for the 6-inch cake) or 2/3 cup (for the 9-inch cake) of the buttercream to garnish the cake.

Assemble the cake:

Using a serrated bread knife, cut off the domed top of each cake so that it is completely level. Break the domed cake pieces into chunks, place them in a food processor. Process the chunks until fine crumbs form. Transfer 1 cup of the crumbs to a medium bowl and set aside. Put the Biscoff cookies in the bowl of the processor (no need to clean it first) and process them to fine crumbs. Stir the cookie crumbs into the cake crumbs.

Using the serrated knife, cut each cake layer horizontally in half to make a total of 4 cake layers. Place one of the layers on a cardboard cake round or cake plate and using a pastry brush, soak it well with the Spiced Soaking Syrup. Using a metal icing spatula, spread a thin layer of cookie butter over the cake layer, then spread a scant ½ cup (for the 6-inch cake) or a full ½ cup (for the 9-inch cake) of buttercream on top of it, covering it completely. Top with another cake layer and repeat the soaking and layering, ending with the last cake layer. Spread a thin layer of buttercream over the top and sides of the cake (this is a crumb coat). Refrigerate the cake for about 20 minutes, to chill the buttercream. Spread the remaining buttercream over the top and sides of the cake, making the buttercream as smooth as possible.

Pat the reserved cake crumbs gently and evenly around the side of the cake (you can coat the entire side or just the bottom half, as you prefer).

Put the reserved buttercream in a pastry bag fitted with a 0.63-inch open star tip (such as Ateco #828). Pipe large star dollops around the edge of the cake. Garnish with some of the cake crumbs. Serve the cake at room temperature. Store leftover cake in the refrigerator.