Preheat the oven to 350°F and prep a 12-count cupcake pan with liners.
Add the butter, sugar, and cookie butter to a large mixing bowl and beat with an electric hand whisk until smooth and creamy, about 3 minutes.
2/3 cup unsalted butter softened, ¾ cup brown sugar, 2 tbsp cookie butter
Add the vanilla and the eggs one by one, beating after each addition until combined.
3 medium eggs, 1 teaspoon vanilla extract
In a separate bowl, whisk together the flour, salt, cinnamon, baking powder and baking soda.
1 & ¼ cups all-purpose flour, ¼ teaspoon salt, ¼ teaspoon cinnamon, ½ teaspoon baking powder, ½ teaspoon baking soda
Add the dry ingredients to the bowl with the wet ingredients and gently fold together until just combined.
Distribute the cupcake mixture between your 12 cupcake cases. Each should be approx. 2/3 of the way full.
Bake for 18-22 minutes or until a skewer poked into the center of a cake comes out clean.
Leave in the pan for about 10 minutes before transferring the cakes to a wire rack to cool completely.
Make the cookie butter frosting:
Add the butter to a large mixing bowl and sift in the powdered sugar. Mix with an electric hand mixer, mix until combined and fluffy, 3 minutes.
¾ cup unsalted butter, 1 & 1/3 cups powdered sugar
Add the cookie butter and milk and beat again until smooth and fluffy. The frosting should be spreadable but still hold its shape when spooned out of the bowl.
1 cup cookie butter, 1-2 tablespoons milk
Assemble the cupcakes:
Spread or pipe the frosting onto the cooled cupcakes. I used a piping bag fitted with a Wilton 1M nozzle to pipe swirls on top.
Decorate each cupcake with a drizzle of melted cookie butter and some Speculoos cookie crumbs if desired.
melted cookie butter, crumbled Speculoos cookies
Notes
Nutrition is calculated without additional garnishes.
For the fluffiest cupcakes, use room temperature ingredients.
A piping bag with a star nozzle creates professional-looking frosting swirls.
Adding a piece of cupcake on top of the frosting with a dollop of Biscoff spread makes for an eye-catching decoration.
For best results, mix the cupcake batter on medium speed to incorporate air without overmixing.
Experiment with different brands of cookie butter for varying depths of Biscoff flavor.