Step 1

Combine the flour, baking powder, baking soda, and salt in a large mixing bowl, set aside

Step 2

Beat butter, sugar, and egg with an electric mixer on medium-high speed until fluffy, about 3-5 minutes.

Step 3

Add the sour cream and vanilla and blend on medium-low until combined.  Mix in the flour mixture, I cup at a time, until just combined.  Dough will be very soft.  Cover and refrigerate the dough 1 hour.

Step 4

Preheat oven to  Prepare baking sheet with parchment paper or cooking spray.  Drop cookie dough by rounded tablespoons 2 inches apart.

Step 5

Bake 10-12 minutes until edges are golden brown.  If baking two sheets at a time, rotate halfway through the baking time.

Step 6

After cookies have cooled completely, mix the glaze by combining all ingredients.  Dip cookies in the glaze and sprinkle with sugar or sprinkles.  Let dry and store at room temperature until serving.