Fantastic Frittatas

I love frittatas! There are a million ways to make them. Here's one of my favorites. 

Frittata with Asparagus, Ham, and Gruyere

6 large eggs, lightly beaten 
1/2 cup shredded Gruyere 
1/4 teaspoon salt
1/4 teaspoon pepper
8 ounces Asparagus, trimmed of tough ends and cut on to bias into 1/4 inch pieces
2 ounces deli ham, sliced 1/4 inch thick, and cut into 1/2 inch cubes
1/2 cup onion, chopped fine
2 tablespoons minced fresh parsley

Adjust an oven rack to the upper-middle position and heat the oven to 350 degrees. 
Whisk together the eggs, Gruyere, salt and pepper. 
Heat oil in a 10-inch nonstick ovenproof skillet over medium heat until shimmering. 
Add the onion, asparagus, and ham and cook until softened, about 4 minutes. 
Add the eggs and parsley, cook about 1 minute. 
Gently pull the cooked eggs back from one edge of the skillet and tilt the pan, allowing any uncooked egg to run to the edge of the skillet. Repeat this process, working around the skillet until the egg on top is mostly set but still moist, 1-2 minutes. 
Transfer the skillet to the oven and bake until the frittata top is set and dry to the touch, about 3 minutes. 
Run a spatula around the skillet edge to loosen the frittata and invert it onto a serving plate. Let stand 3-4 minutes before serving.