Step 1

In a large bowl, cream the butter and sugar together until light and fluffy, about 3 minutes. You can use a stand mixer, an electric hand mixer, or a fork and some elbow grease to do this. It's up to you.

Step 2

Add the egg and vanilla, and stir until very smooth.

Step 3

Add the Greek yogurt, and stir until combined.

Step 4

Add the baking powder, baking soda, salt, and all-purpose flour and stir until well combined. The dough will be sticky.

Step 5

Place the dough on a piece of plastic wrap, shape into a disk, wrap well, and refrigerate for at least 4 hours and up to 36 hours.

Step 6

When you are ready to bake the dough, remove it from the fridge, unwrap, and divide it into 2 pieces. Roll the dough out to 1/2-inch thick on a well-floured surface, and cut into shapes (I used a 3-inch circle cookie cutter). Place the cut out cookies on a parchment- or baking-mat-lined cookie sheet, and bake at 350 degrees F. for 10-11 minutes. The tops of the cookies will be light but the bottom should be lightly brown.

Step 7

Repeat with remaining dough.

Step 8

To make the frosting, add the butter, vanilla, 1 tablespoon of cream or milk, and the dash of salt to a large bowl, and beat until fluffy, about a minute (a stand or hand mixer works well for this). Add the powdered sugar, and beat until smooth and fluffy. If the frosting is too thick, add the additional tablespoon of cream or milk and beat again.

Step 9

When the cookies are completely cooled, add a generous helping of frosting and sprinkles.