the butter in a heavy saucepan
and saute the garlic and onions
until translucent, about 10 minutes. Add the ketchup, sugar, vinegar, Worcestershire, tomato paste, chili powder, salt, black pepper and cola and simmer
until the flavors have blended, about 15 minutes. Stir and continue cooking until the sauce begins to thicken, 20 to 30 minutes longer, and then taste and adjust the seasonings with salt and black pepper, if desired. Remember, the ribs will have plenty of spice rub on them, so don't over-season the sauce.
Let the sauce cool until it is warm but no longer "boiling" hot, about 10 minutes. Puree with an immersion or traditional blender
(this will make the sauce thicker). Continue to let cool. Brush on food 5 to 15 minutes before the end of cooking time, or keep tightly covered in the refrigerator for up to 2 weeks. Yield: 5 cups.