Preheat oven to 350 degrees F.
Whisk together eggs in large bowl and season with salt and pepper. Stir in chives and set aside.
In large oven-proof skillet, add butter or olive oil over medium heat.
Add garlic and cook one minute.
Add diced onions and cook until beginning to soften, about 5 minutes.
Add asparagus and cook 5-7 minutes, until it is beginning to soften and turns bright green, stirring often.
Add prosciutto and stir to evenly distribute then sprinkle with goat cheese.
Pour egg mixture over veggies.
Bake in preheated oven for 12-15 minutes, until frittata is cooked through. The cooking time will be dependent on how large your skillet is. I used a 10" skillet. If yours is smaller and deeper, it will likely take closer to 20 minutes to cook through. If it is wider and more shallow, it will be closer to 12 minutes. You just want to make sure the eggs are cooked and the center is not runny.
Let cool slightly, then cut into slices.