In an oven-safe skillet, melt butter and saute zucchini, tomato and mushrooms to soften, 1 to 2 minutes.
3
In a medium bowl beat together eggs, milk, mustard, seasonedsalt and lemon pepper. Stir in Swiss cheese. Pour over vegetables and cook, without stirring, over low heat until eggs are just set, about 10 minutes.
4
Broil for 2 to 3 minutes to brown the top. Carefully slide frittata out of skillet and cut into wedges to serve.
