Mix up the sugar cookies according to package directions, OR make your own sugar cookie recipe.
Spray a mini muffin tin with cooking spray (I like Baker's Joy for baking!), and preheat the oven to 375 degrees, or 350 for dark or nonstick pans.
Press cookie dough firmly into each tin, onto the sides and bottom. Bake for 9-11 minutes, or until cookie cups are lightly brown. Cool completely, then remove from muffin tin.
While the cookie cups are baking, make your frosting! Add the shortening and butter to the powdered sugar, and beat while slowly adding the milk or cream. Start with just a tablespoon, then if it's too thick, add another tablespoon. Add the vanilla and salt, then beat on high for a minute or so until the frosting is thick and creamy.
When the cookie cups are cool, add the frosting to a sandwich bag, push it to one corner, then snip off the corner of the bag. Pipe frosting into each cookie cup and top with sprinkles!
Refrigerate until ready to serve!