Filling

Cup of Yum
1. Line a small baking sheet or a plate with wax paper and set aside.
2. Scoop biscoff by 2 teaspoon (11g) sized scoops and dollop onto prepared sheet. Place in the freezer while you prepare your cookie dough (at least 20 minutes).

Cookie Dough

1. Combine butter and sugar in a large mixing bowl and use an electric mixer (or a stand mixer with paddle attachment) to beat until light and creamy and well-combined.
2. Add egg, egg yolk, and vanilla extract and stir well.
3. In a separate, medium-sized mixing bowl whisk together flour, cream of tartar, cornstarch, baking soda, cinnamon, and salt.
4. Gradually (in 3 or 4 parts) add the dry ingredients to the wet, stirring until all flour mixture is completely incorporated.
5. Scoop dough by 2 Tablespoon-sized (44g) scoops, gently roll between your palms to make a smooth ball, and press your thumb into the center to make a deep indent into the center of the dough. Retrieve a cookie butter ball from freezer and press into the indent. Form the dough over the cookie butter to completely conceal it and roll between your palms again to make a smooth, even ball.
6. In a small bowl, whisk together sugar and cinnamon. Roll dough balls through the mixture, evenly coating the cookie with cinnamon and sugar. Place dough balls on a wax paper lined plate or baking sheet in the freezer for at least 15 minutes before baking.
7. Meanwhile, preheat your oven to 350F (175C) and line several baking sheets with parchment paper.
8. Once dough has chilled, transfer cookie dough to prepared baking sheet, spacing cookies at least 2” (5cm) apart.
9. Transfer to center rack of 350F (175C) oven and bake for 12-13 minutes, until edges are just beginning to turn a very light golden brown.
10. Allow to cool completely on the baking sheet before enjoying!