• Preheat oven to 375°F. Place 12 muffin liners into a standard muffin pan and set aside.

Make the crust.

• Add biscoff cookies and brown sugar to the bowl of a food processor. Pulse until there are fine crumbs with no large chunks remaining.
• Add melted butter and blend until combined and the crumbs begin to stick together.
• Divide the crust among the 12 muffin liners and press the crumbs into a solid crust using the back of a spoon. 
• Bake the crusts for 5 minutes, then remove the pan from the oven and turn the oven down to 325°F. Let the crusts cool while you prepare the cheesecake.

Make the cheesecake.

• In a large bowl, add cream cheese, cookie butter, sugar, sour cream, heavy cream, vanilla, and salt. Using an electric handheld mixer, beat well on medium speed until smooth.
• Add egg and yolk and beat on low speed just until combined.
• Spoon cheesecake onto the crusts so that muffin liners are nearly filled. (You'll use about 3 Tablespoons of cheesecake per liner, and you may have a little bit of cheesecake leftover.)
• Return the pan to the 325°F oven and bake for 15 minutes or until the edges of each cheesecake are set but the centers still wobble slightly when you jiggle the pan. Turn off the oven and let the cheesecakes sit in the warm oven with the door closed for 10 minutes. Then crack the oven door open and let the cheesecakes sit for another 10 minutes. Next transfer the pan to a wire rack and allow the cheesecakes to cool completely (about 1 hour). Finally, transfer the pan to the fridge and chill the cheesecakes for at least 2 hours and up to overnight.

Garnish the cheesecakes.

• Once the cheesecakes have chilled and set, heat the cookie butter topping in the microwave on 50% power until it's pourable.
• Spoon or drizzle 1 teaspoon of cookie butter onto each cheesecake.
• Chill cheesecakes for 30 minutes to let topping solidify. Then let rest at room temperature for 5 to 10 minutes before serving.