Place vegetables and butter in food processor or blender. Process until smooth.
Variations: Herbs and spices add another dimension to vegetable purees.
Here are a few suggestions.
Cauliflower: Add curry powder or 1/2 cup shredded Swiss or Cheddar cheese.
Broccoli: Add a pinch of cayenne pepper.
Zucchini, pattypan, or crookneck squash: Add a few sprigs of dill weed.