In 2-quart heavy saucepan, stir hot water, 1 1/2 cups milk, 2 tablespoons of the butter, and the sauce mix and uncooked pasta (from Chicken Helper box). Heat just to boiling, stirring frequently. Reduce heat; simmer uncovered about 10 minutes, stirring occasionally, until pasta is tender. Add cauliflower and frozen peas to pasta. Cook 2 minutes longer. Keep warm.