Blend the eggs, juice, mustard, and garlic (if using) until smooth.

While the blender is running, slowly pour in the olive oil in as thin a stream as you can manage. This will allow it to emulsify so that it won't separate when stored.

Preheat the oven to 350F. Slice off the top and bottom of each garlic bulb. Peel off the outer skins.

Coat each bulb in 1 tablespoon of cooking fat.

Wrap each bulb in foil. Bake for 45 minutes.