In a mixer, mix the butter until it’s creamy. Continue mixing and add the sugar gradually until you have a fluffy texture.
Then add the eggs, one at a time, until all is combined.
Stir in the vanilla. Do not over mix.
In a separate bowl, combine your flour, cream of tartar, baking soda, and salt.
Add the flour mixture to the butter mixture one cup at a time and stir it by hand until it is the consistency of firm cookie dough.
Form the dough into a ball and place it in a covered bowl. Chill for several hours or overnight.
Preheat your oven to 375 degrees Fahrenheit. Take your baking sheet and line it with parchment paper.
Take your dough and roll it out about 1/8 inch thick. Cut out some cookies with a larger heart shape or a cutter of your choice. (For the larger cookies I used a heart, a square, and also a circle.)
Set 1/2 of your shapes to the side for the cookie bottoms. For the other half that are the “tops”, cut smaller heart shapes out with a smaller heart cookie cutter. You can save these tiny hearts and bake them for extra fun tiny cookies as well!
Bake all the cookies at 375 for 6-8 minutes until golden brown on the bottoms. The cookies themselves remain light in color.
Cool your cookies on a wire rack.