Preheat the oven to 350°F. Line a 12-cup muffin tin with muffin liners.
In a medium bowl, sift the flour. Add the baking powder, baking soda, and salt. Using a food processor, blend the Biscoff cookies into a fine crumb and add to the dry ingredients.
1 ⅓ cups All-purpose flour, 1 teaspoon Baking powder, ¼ teaspoon Baking soda, 1 teaspoon Salt, ½ cup Biscoff cookie crumbs
Using a mixer, beat the butter and sugar on high speed for 3 minutes. Scrape the bowl and add the sour cream and vanilla. Mix until just combined.
½ cup Unsalted butter, ¾ cup White granulated sugar, 1 teaspoon Pure vanilla extract, ⅛ cup Sour cream
Add in the eggs and mix in on medium until combined.
2 Large eggs
Add in ⅓rd of the dry ingredients and half of the buttermilk and mix on low speed. Then, add another ⅓rd of the dry ingredients and the rest of the buttermilk. Finish with the rest of the dry ingredients. Scrape the bowl with a rubber spatula.
½ cup Buttermilk
Use a 2oz cookie scoop and scoop the batter into the muffins liners. Fill it ¾ths full.
Bake for 18-20 minutes until a toothpick inserted comes out clean.
Let the cupcakes sit in the hot pan for 10 minutes before transferring to a cooling rack. Cool the cupcakes completely.
Use a cupcake corer or a sharp knife to cut a hole into the middle of the cupcake. Go ½ way down the cupcake and toss the tops.
Melt the cookie butter in the microwave for 20 seconds. Fill the cupcakes with the melted cookie butter.
⅓ cup Biscoff cookie butter