Hi sherri. Lisa's post looks terrific. If I might add something, below is my Italian grandmother's recipe for her frittata. HOWEVER! I'm sure I don't have to tell you how rubbery eggs become when reheated. I'm a bit familiar with Kosher restrictions, but you mentioned that you can reheat it the day you serve it. If that's the case, undercook the frittata so that when it's reheated, it will be perfect (I hope!) Multiply the ingredients for more than 4 people.
FRITTATA (Italian Omelet)
Serves 4
1 zucchini, peeled and sliced into 1/8" slices
1 large sweet, white onion, like Vidalia, sliced into wedges
6 eggs
2 tablespoons olive oil
2 tablespoons butter
salt and pepper to taste
thinly sliced muenster cheese

1 deep frying pan - preferably cast iron

Preheat oven to 375.
Coat a large frying pan with the olive oil. Add the onion and cook slowly over low heat until translucent.
Add the zucchini to the skillet and cook until soft, about five minutes. Season with salt and pepper.
Beat the eggs and add them to the pan, pouring them over the vegetables. Stir gently to combine.
Reduce heat and cook the mixture over low heat for about 15 minutes or until the edges begin to look dry.
Remove the pan from heat, cover the top of frittata with cheese and transfer it to the oven.
Bake for about 2 minutes or until set in the center and cheese is melted.
Remove from oven and allow frittata to set.
To serve, cut into wedges. Serve with toasted Italian bread.
Good if served at room temperature.