These lemon sugar cookie cups are like mini lemon pies with a sugar cookie crust - easy to make, they're the perfect little sweet treat! Your own little pocket of sunshine.
Cream together the butter, oil, sugar, powdered sugar, water, eggs and vanilla until smooth and well combined.
In a large bowl, whisk together the flour, salt, baking soda and cream of tartar.
Add the dry ingredients to the butter mixture 1 cup at a time, mixing after each addition, until all of the dry ingredients have been incorporated into the dough.
Roll the dough into 1 tablespoon sized balls and place them in the lightly greased cups of a mini muffin tin.
Use the rounded bottom of a 1/2 tablespoon sized measuring spoon to press a well in the middle of each cookie.
Bake the cookies for 9-10 minutes, or until they are lightly browned on the edges.
Remove them from the oven and re-press the well in the cookies while they are still warm.
Let them cool completely in the muffin tin, then use the tip of a sharp knife to pop them out of the tin.
Fill the wells in the cookie cups with 1/2 tablespoon of lemon curd.
Store the cookie cups in an airtight container in the refrigerator and serve chilled. The cookies also freeze well for up to 3 months.