Preheat the oven to 350℉ (177℃). Generously grease and flour a 10–12 cup Bundt pan, making sure to coat all of the crevices. Tap out the excess flour.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon.
2 ¾ cup (388g) all-purpose flour, 2 teaspoons baking powder, ½ teaspoon baking soda, ¼ teaspoon salt, 1 ½ teaspoons ground cinnamon
In a large mixing bowl with a hand mixer, beat the softened butter, Biscoff spread, brown sugar, and granulated sugar until light and creamy, about 2–3 minutes.
¾ cup (170g) salted butter, ¾ cup (177g) Biscoff cookie butter spread, 1 cup (200g) packed light brown sugar , ½ cup (100g) granulated sugar
Add the eggs one at a time, mixing well after each addition. Mix in the vanilla extract.
4 large eggs, 2 teaspoons pure vanilla extract
Add the sour cream and mix until combined.
1 cup (230g) sour cream
Gradually add the dry ingredients to the wet mixture, alternating with the milk. Mix just until combined and no dry flour streaks remain. Gently fold in the chopped Biscoff cookies with a spatula.
½ cup (118ml) whole milk, 1 cup chopped Biscoff cookies
Spoon the batter evenly into the prepared Bundt pan and smooth the top.
Bake for 45–55 minutes, or until a toothpick inserted into the thickest part of the cake comes out clean or with a few moist crumbs.
Let the cake cool in the pan for 15 minutes, then carefully invert it onto a wire rack. Allow the cake to cool completely before decorating.
In a medium bowl with a hand mixer, beat the cream cheese, vanilla, and butter until smooth and creamy.
8 ounces cream cheese, ¼ cup (57g) salted butter, 1 teaspoon pure vanilla extract
Add the powdered sugar gradually and beat until light and fluffy.
2 cups (240g) powdered sugar
Transfer the frosting to a piping bag with a large round tip. Pipe thick lines of frosting back and forth over the Bundt cake, following the ridges and allowing the frosting to fall slightly down the sides.
Add the Biscoff spread to a microwave-safe bowl and microwave for about 15 seconds, then stir until smooth and pourable. Let cool slightly, then drizzle the melted Biscoff mixture over the cream cheese frosting.
½ cup (118g) Biscoff cookie butter spread
Sprinkle the chopped and crushed Biscoff cookies generously over the top.
5-6 Biscoff cookies, 2 Biscoff cookies