Whisk together first 4 ingredients at least 1 minute or until well blended.
Melt butter in a 12-inch ovenproof skillet over medium heat; remove skillet from heat, and pour half of egg mixture into skillet. Sprinkle evenly with cooked sausage and cheese. Top with remaining egg mixture.
Bake at 350° for 15 to 20 minutes or until set.