Preheat oven to 375°F.

In a mixing bowl, whisk together flour, baking soda, baking powder, cream of tartar, and salt. Set aside.

In a large mixing bowl or metal bowl of a stand mixer, add the butter and sugar (1 1/2 cup). Cream together for 3-4 minutes until it is light and fluffy. Add the eggs, vanilla extract, and Biscoff spread to this mixture. Beat for 1 more minute until fully incorporated.

Add the dry ingredients and mix together until combined.

Prepare your cinnamon sugar mixture by whisking together 4 tablespoons of sugar with 2 tablespoons of cinnamon.

For even better cookies and if you have the time, portion the dough into small bowls and place on a baking sheet and chill for about 25 minutes. Otherwise, just portion the dough and roll in the cinnamon mixture right away. Make sure the cookie is fully coated and the cinnamon mixture is pressed on to the cookie. Do not overcrowd the cookies. They will spread.

Bake for 10-12 minutes or just until the edges develop a golden color. If your cookies are larger like mine, 12 minutes is perfect. 10 minutes for smaller sized cookies. Once the cookies are done baking, allow them to rest on the baking tray to set. They will be very soft straight out of the oven but they'll firm up while still being super soft and chewy.