Preheat your oven to 350°F/180°C. Line a 9×13-inch baking pan with parchment paper, ensuring the paper hangs over the sides for easy removal later. Set aside.

Crush the Biscoff cookies until they become fine crumbs, using a food processor or blender. In a medium mixing bowl, combine the crumbs with melted butter and salt.

Press the crumb mixture into the prepared baking pan, creating an even layer covering the bottom.

Bake at 350°F/180°C for 10 minutes. Then, remove from the oven and let it cool on a wire rack while keeping the oven on.

In the bowl of a stand mixer or a large mixing bowl if using a hand mixer, combine softened cream cheese and sugar. Beat on medium speed until smooth and creamy.

Add cookie butter, sour cream, and vanilla extract. Beat until well mixed, scraping down the sides of the bowl as needed.

Add the eggs, one at a time, mixing just until each egg is incorporated. Avoid overmixing.

Pour the filling into the crust and spread it out evenly with a spatula.

Bake at 350°F/180°C for 30-35 minutes, until lightly browned and the center is set (it's okay if it's soft, as long as it's not liquidy).

Let the cheesecake cool in the pan on a wire rack until it's cool to the touch. Then, transfer it to the refrigerator and chill for at least 4 hours

Microwave the cookie butter in a microwave-safe bowl for about 30 seconds. Stir well.

If necessary, microwave for an extra 15 seconds and stir again.

Pour the melted cookie butter over the chilled cheesecake and spread it evenly.

Put the pan back in the fridge and let it chill for 30 minutes until the topping sets.

Slice into squares and serve.