Heat an oven-safe large (10 inches) non-stick skillet on the stove over medium heat.
While the skillet is heating, prepare your ingredients. Dice your ham into 1/2 inch pieces. Finely dice your onion and bell pepper.
Add the oil to the hot skillet. Add the onion and bell pepper and cook until just tender, approximately 3-5 minutes.
While the vegetables are sauteeing, in a medium bowl whisk together the eggs, cheddar cheese, salt, and black pepper.
When the vegetables are ready, add the ham and stir to evenly distribute with the vegetables. Add the egg mixture to the skillet. Stir very lightly. Let the egg mixture sit and cook on the stove until the edges are just set, approximately 5 minutes.
Turn the stove off and place the skillet in the oven. Let the frittata cook until it is cooked through and dry to the touch on top, approximately 10-13 minutes.
Use a rubber spatula to loosen the frittata and either slide out or flip onto a plate. Serve immediately.
Notes
The smaller the skillet, the thicker your frittata will be and the longer it will need to cook. The larger the skillet, the thinner the frittata and the faster it cooks. I use a 10 inch skillet for this recipe.A non-stick skillet is best, but you can also use a cast iron skillet. The egg tends to stick more in cast iron, making it difficult to flip out if you choose to do so.