To make it...
Place the potatoes in a large saucepan with the garlic and enough lightly salted water to cover. (Can be done to this point up to 4 hours ahead. Cover and refrigerate.) Place over high heat and bring to a boil. Reduce heat to low, cover, and simmer 15 to 20 minutes or until fork-tender. Drain. Beat with an electric mixer or mash with a potato masher until smooth. Add the butter. Gradually add the milk until the potatoes are fluffy. Blend in the salt and herbs.
To fake it...and save 30 minutes
Heat two 20-oince packages red mashed potatoes according the label directions. Beat in one 2-ounce package Boursin or another garlic herb cheese.
Really good. I only had red potatoes but it worked just fine.