Step 1 In a large skillet, cook the chopped bacon over medium-high heat until browned and crisp, stirring frequently, about 15 minutes.
Step 2 To the pan, stir in the green onion, onion, chopped garlic, salt and pepper and simmer, stirring frequently, until the vegetables are tender, 10 to 12 minutes. Remove from heat.
Step 3Stir in the butter, then puree the mixture in a blender. (The base can be made ahead of time to this point and covered and refrigerated. Reheat before using.)