Heat your oven to 375°F (190°C). Cut 1/4 inch (6mm) off the head of garlic and place the head, cut side up, on a big square of aluminum foil. Give it a splash of water and a splash of olive oil. Bring the corners of the foil up over the garlic to make a loosely wrapped little package. Bake for about 45 minutes. Remove the garlic from the oven and let it cool in the foil. Squeeze the roasted garlic out of 4 or 5 cloves and save the rest to spread on grilled bread with salted butter.
Put the roasted garlic, the raw garlic, clove, mustard, vinegars, egg yolks, anchovies, and lemon juice into a blender or food processor and blend for 30 seconds or until combined.
With the machine running, add the olive oil in a slow, stead stream until it's incorporated and the dressing looks smooth. Taste and add salt, pepper, and more lemon juice as desired. The dressing will keep for a week in the refrigerator.