If you used unsalted butter, optionally reserve the milk solids & water. Then heat them in a shallow pan to drive off the last of the moisture, and allow them to brown a bit. Use them for various uses like dressing vegetables, mixed into mashed potatoes or rice, or kneading into bread dough. Mixed back into butterfat they take on an amazing flavor profile and consistency, though it lowers the smoke point. If you started with salted butter, once the water is driven out the milk solids would be so insanely salty they are probably not practical for any use.