Beat together butter, vanilla, 1 tablespoon cream, and a half cup powdered sugar; stir in a few drops food coloring - The color should be somewhat darker than desired, because it will lighten up as you add more cream and sugar to the frosting.
Add alternating portions of 1-2 tablespoons cream then a half cup powdered sugar; beating after each addition until well blended.
Continue adding and beating in portions of cream then powdered sugar until you have incorporated all the ingredients; stir in additional cream or powdered sugar if necessary.
You may vary the amounts of cream and/or powdered sugar to achieve desired frosting amount and consistency - Your choice of a nice and thick frosting, a very thin glaze, or anything in between is possible.
Spread finished frosting onto cooled sugar cookies; candy sprinkles are best added as each cookie is frosted - They seem to adhere better that way.
NOTE: Regular or evaporated milk, whipping cream, whipped cream, or even sour cream - whatever you've got in the fridge - may be substituted (I've subbed in each of these at times) for the half & half.