Preheat your oven to 350°F (175°C). Grease and flour two 8-inch round cake pans, then line the bottoms with parchment paper. This ensures easy release.

In a large bowl, whisk together the sifted all-purpose flour, granulated sugar, baking powder, baking soda, and salt. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, cream the softened butter on medium speed until light and fluffy, about 2-3 minutes. Scrape down the sides of the bowl.

Add the eggs one at a time, beating well after each addition until fully incorporated. Mix in the vanilla extract and 1/2 cup creamy Biscoff spread until smooth.

Gradually add the dry ingredients to the wet ingredients in three additions, alternating with the buttermilk in two additions, beginning and ending with the dry ingredients. Mix on low speed until just combined, being careful not to overmix. Overmixing can lead to a tough cake.

Divide the batter evenly between the prepared cake pans. Smooth the tops with a spatula.

Bake for 30-35 minutes, or until a wooden skewer inserted into the center of the cakes comes out clean. The cakes should be lightly golden and spring back when gently pressed.

Remove cakes from the oven and let them cool in the pans on a wire rack for 10-15 minutes before inverting them onto the wire rack to cool completely. Ensure cakes are entirely cool before frosting (at least 1 hour).

In the bowl of a stand mixer fitted with the paddle attachment, beat the softened butter on medium-high speed for 3-5 minutes until very light and fluffy. This step is crucial for airy buttercream.

Gradually add the sifted powdered sugar, 1 cup Biscoff spread, vanilla extract, and salt. Start on low speed to avoid a sugar cloud, then increase to medium-high and beat until combined and smooth.

With the mixer running on low, slowly add 2 tablespoons of heavy cream or milk. Increase speed to medium-high and beat for another 2-3 minutes until light, fluffy, and spreadable. Add more cream/milk, a teaspoon at a time, if needed, to reach your desired consistency.

Once the cake layers are completely cool, level them if necessary using a serrated knife for even layers.

Place one cake layer on your serving plate or cake stand. Spread about 1 cup of Biscoff buttercream evenly over the top.

Carefully place the second cake layer on top. Frost the top and sides of the entire cake with the remaining Biscoff buttercream, using an offset spatula to create smooth or decorative swirls.

For garnish, gently press crushed Biscoff cookies around the base or top edge of the cake. If desired, melt 2-3 tablespoons of Biscoff spread in the microwave for 15-20 seconds until drizzly, then drizzle it over the top of the cake, letting some drip down the sides.

Serve immediately or chill for best flavor and texture. Enjoy your Ultimate Biscoff Dream Cake!