Step 1

Preheat the oven to 350°F (180°C). Line an 8x8 baking pan with parchment paper. Leave a paper overhang, so you can easily lift the baked cookie from the pan once baked.

Step 2

In a small bowl, whisk together the flour, cream of tartar, cinnamon, baking soda, and salt. Set these dry ingredients aside.

Step 3

In a large bowl, add the room temperature butter and granulated sugar. Beat them together with an electric mixer for about 2-3 minutes until lighter in color and creamy. If you have no electric mixer, beat them together with a wooden spoon until creamy.

Step 4

Add in the egg and vanilla and beat until combined.

Step 5

Add the dry ingredients to the wet ingredients. Beat together on low speed to combine it all into a thick but slightly sticky cookie dough.

Step 6

Scoop the cookie dough into the prepared pan. Use an offset spatula to press the cookie dough out evenly.

Step 7

Mix together the granulated sugar and cinnamon for the topping. Sprinkle this in an even layer on top of the dough

Step 8

Bake for approximately 18-20 minutes, until the edges are baked and the middle is just set. Don't over-bake them.

Step 9

Let the pan cool for 10 minutes before removing the cookie. Let it cool further on a wire rack.

Step 10

Once cooled, cut into 16 pieces.