Heat the oven to 350 degrees Fahrenheit.
In a medium bowl, whisk the eggs with cream, ½ teaspoon of the salt, pepper, and the cheese.
Heat the olive oil in an oven-safe 10-inch skillet (non-stick or a well-seasoned cast iron pan are best).
Add the zucchini, onions, and bell pepper. Cook, stirring every once and a while until the onions are soft and the zucchini and bell peppers have a little color; about 5 minutes.
Season with ¼ teaspoon of salt then add the spinach. Toss the spinach around the pan until it’s ever so slightly wilted and bright green.
Turn the heat to low. Give the egg mixture another whisk then pour into the skillet. Shimmy the pan back and forth a bit to distribute the egg around the vegetables.
When the edges of the frittata begin to set and turn lighter in color, slide the skillet into the preheated oven; about 1 minute.
Bake for 20 to 30 minutes, until the eggs are barely set and the frittata trembles — like jello — when you give the pan a gentle shake. Keep an eye on it as it bakes and check the frittata a few minutes before it’s supposed to be done. You are not looking for a brown top, just one that looks cooked and barely set.
Serve the frittata hot or cold with fresh herbs on top.
