Combine butter, oil, sugars and vanilla until smooth. Blend in eggs.
Add flour, salt, cream of tarter and baking soda until blended in.
Press dough into a greased dish.
Bake 20 minutes watching carefully as to not over bake.
Adjust baking time based on what type of dish you use. You can use a pizza pan, cake pan, pie dish, tart pan or springform pan. The thicker your cake is, the longer it will need to bake.
I baked a slightly smaller, thick sugar cookie cake, which required 20 minutes - baked to perfection. If there's anything I can recommend in life it's that you should never over-bake your cookies.
If you're newer to baking, you can certainly mix this recipe by hand. However, I love using my stand mixer fitted with a flat edge beater.
Decorate however you'd like! Get creative! We love to frost our cookie cakes, but any type of candy toppings look cute as well. You can also simply top with a little homemade whipped cream and a sprinkling of confectioners sugar.
I slightly under-bake just about everything for that melt-in-your-mouth texture we've all come to love about sugar cookie cake!