Line a cookie sheet with a silicone mat or parchment paper. Set aside.

In a large mixing bowl, mix the butter, sugar, brown sugar, and vanilla extract. Mix with a hand mixer until all ingredients are combined, light, and fluffy.

Add the eggs and mix well in between each one. Set aside.

In a separate bowl, whisk the flour, baking powder, baking soda, and cream of tartar together.

Add the dry mixture to the butter mixture. Mix until flour is all incorporated and you have a cookie dough. Set aside. For this step, I used my Danish dough whisk. This way I make sure I don’t overmix the batter.

In a smaller bowl, mix the ingredients for the swirl; butter, brown sugar, cinnamon, and salt. Mix until all ingredients are combined.

Add the swirl mixture to the cookie batter. Use a spatula and mix “LIGHTLY” the swirl into the cookie batter. Use the same motion as folding an egg or meringue into a batter. Don’t overmix, you still want to see the swirl.

Use a medium size cookie scoop (about 1 ½ tablespoons) and scoop the dough into a ball.

Place on the prepared cookie sheet and press down the ball to make a thick disc.

Fill the cookie sheet leaving 1 ½ inch space between each cookie.

Bake in the preheated oven for 10-11 minutes. The edges of the cookies will be set and golden.

Cool the cookies in the pan for 1-2 minutes then transfer them to a cooling rack.

Repeat with more cookie dough. If, like me, you have a warm kitchen you might want to keep the uncooked batter in the fridge in between batches.