Make toffee first (or use store-bought)

Line 2 baking sheets with parchment paper and set aside.

In a small bowl, combine ¼ cup sugar with 3 tablespoons of cinnamon and set cinnamon sugar mixture aside.

In a mixing bowl, combine flour, baking soda, salt, and cream of tartar and set flour mixture aside.

In another mixing bowl (if using a hand mixer) or in the bowl of a stand mixer with the paddle attachment, cream together the butter, brown sugar and remaining 1 cup of white sugar. Scrape down the sides of the bowl as needed. When this mixture is completely combined, add eggs, one at a time while the mixer runs on low speed, and mix until just combined and then add vanilla and mix again until just combined.

Next, add the dry ingredients to the wet and mix until all ingredients are combined.

Remove the bowl from the stand mixer, if using, and use a wooden spoon or study silicone spatula to mix in toffee bits.

Use a large cookie scoop for slightly overfilled scoops of cookie dough, roll into a ball, and roll each cookie dough ball in the prepared sugar-cinnamon mixture then set on the prepared baking sheet. Place up to 8 cookie dough balls on each cookie sheet, evenly spaced apart, and chill prepared trays of cookie dough in the fridge for 30 minutes. if you used softened butter, chill cookie dough on baking sheets for one hour before baking.

Preheat oven to 350 degrees.

Bake 2 trays at a time for 15-16 minutes, rotating and swapping racks halfway through bake time. Bake until cookie edges are just starting to turn golden brown.

Transfer each tray to a wire rack and let the cookies cool completely.