Preheat the oven to 350℉/180℃ and line two large baking sheets with parchment paper.
In a bowl, whisk together the flour, baking soda, cinnamon and salt.
1¼ cup all-purpose flour, ½ teaspoon baking soda, 1 teaspoon ground cinnamon, ⅛ teaspoon kosher salt
In the bowl of a stand mixer fitted with the paddle attachemnt, cream together the butter and cookie butter until smooth.
¼ cup unsalted butter, ¾ cup cookie butter or Biscoff spread
Add the dark brown sugar and mix on medium speed for two minutes.
¾ cup dark brown sugar
Scrape down the sides, then add the egg and vanilla and mix on medium speed for one more minute.
1 large egg, 1 teaspoon vanilla paste or extract
With the mixer on low speed, spoon in the flour and mix until it's just combined.
Using a 2 tablespoon cookie scoop (or weigh out ~40g balls), scoop and press the dough into the scoop so it's slightly mounded, but almost level.
Place on the cookie sheet and space the dough evenly. I bake 7-8 cookies on a full-sized baking sheet. They should be spaced at least 2 inches apart.
Bake the cookies for 8-9 minutes, remove from the oven, bang the pan on the counter a couple times, then cool for 5 minutes on the pan.
Remove the cookies with a spatula to a wire rack to cool.