1. Preheat the oven to 350 degrees F (175 C). Line two baking sheets with parchment paper and set aside.

2. In a small bowl, whisk together the flour, cinnamon, baking powder, baking soda, and salt. Then set aside the flour mixture.

3. In a large mixing bowl, cream together the softened unsalted butter, packed light brown sugar, and granulated white sugar with an electric hand mixer on high speed until fluffy and light in color, about 3 minutes. Scrape down the sides of the bowl as needed.

4. Add in the room temperature egg yolks and vanilla bean paste or extract. Mix on high speed for another 1-2 minutes until the mixture is pale and even fluffier.

5. Next, add the Biscoff cookie butter to the wet ingredients. Mix on medium-low speed just until fully combined, being careful not to overmix.

6. Gradually add the dry ingredients to the wet ingredients, a little at a time. Mix on low speed, then medium-low speed, just until combined. Stop mixing as soon as no dry streaks remain to prevent tough cookies.

7. Scoop the dough into balls using a 2-tablespoon capacity cookie scoop. Arrange the cookie dough balls about 2 inches apart on the lined baking sheet, typically 6 cookies per sheet to allow for spreading.

8. Bake the cookies for 10-11 minutes, or until the edges are set and lightly golden, but the centers still look slightly soft. This ensures a chewy texture. Let them cool for five minutes on the cookie sheet – they will continue to set during this time.

9. Transfer the baked cookies to a wire rack to cool for 10-15 more minutes, or until cool enough to handle and enjoy. The flavors will deepen as they cool.