Sauté vegetables in a large oven-proof skillet on medium-high for about 5 minutes until just starting to get tender. Do not sauté tomatoes.
Sprinkle one cup grated cheese over vegetables.
While vegetables are cooking, whisk eggs with half-and-half, salt, pepper, and Italian herbs.
Pour eggs over vegetables and cheese. Sprinkle remaining cheese over the top.
If using skillet, cook over medium-high heat for just a minute until edges are starting to set. Then place skillet in oven. If using baking dish, place in oven. Bake about 15-20 minutes or until eggs are set.
Allow to rest for at least five minutes before cutting and serving.
Notes
Tips for Making the Best Frittata:
You can add leftover rice or diced potatoes or even some black beans.
It's best to leave the vegetables in the skillet and pour the eggs into the hot skillet, cooking on medium-high for about a minute so the edges set.
However, if you're cooking for a crowd and need more room you can sauté the vegetables and then combine everything in a large 9 x 13 inch dish.
Allow the baked frittata to rest for at least five minutes before cutting and serving.
The frittata will keep in the refrigerator for a couple of days and is just as good reheated as when you first made it. Just cover with foil and microwave individual servings as needed for just a few seconds.
Don't reheat the whole frittata in the oven as you will over-cook it.
Make-ahead dish: prepare the frittata ahead except for baking, then cover and store in the refrigerator for up to one day. Bake when ready to serve.