What to Do
Prep the Vegetables: Rinse the asparagus, snap off the tough woody ends, and chop the spears into ½-inch / 1 cm pieces. Briefly blanch the asparagus in simmering water for 1-2 minutes until tender-crisp, then drain well.
Whisk the Eggs: In a medium bowl, crack the eggs.
Season with a pinch of salt and pepper, then whisk vigorously until the yolks and whites are fully combined and slightly frothy.
Sauté the Base: Heat the olive oil in a 10-inch oven-safe frying pan over medium heat.
Add the chopped onion and cook for about 5 minutes until soft and translucent.
Stir in the minced garlic and cook for one more minute until fragrant.
Combine and Cook: Add the blanched asparagus to the pan, then pour the beaten egg mixture evenly over the top.
Reduce the heat to medium-low.
Set the Frittata: Cook on the stovetop for 5-6 minutes, until the edges are set but the center is still a bit jiggly.
Add Cheese & Finish: Sprinkle the grated Parmesan cheese over the top. To finish, either cover the pan with a lid, turn off the heat, and let it sit for 5 minutes until the cheese is melted and the center is set, OR place the pan under your oven's broiler for 2-3 minutes until the top is golden and puffed. Watch it carefully to prevent burning.
Serve: Let the frittata rest for a minute before slicing into wedges.
Serve warm or at room temperature.
Don't overcook! The frittata is done when the center is just barely set. It will continue to cook from residual heat after you remove it from the stove or oven.