Cream together butter and sugar until fluffy.
Add in eggs and vanilla extract until mixed well.
Slowly add in flour and baking powder.
Covered in plastic wrap and refrigerate for 1 hour.
Preheat oven to 350.
Form the cookies with a teaspoon and roll in your hands to create a ball. Roll the cookie dough ball into your sugar & instant coffee mix until coated.
Place on cookie sheet about an inch apart and bake for approximately 10 minutes.
Remove from oven and allow to cool before transferring to cooling rack.