Preheat your oven to 375°F (190°C).
In a medium mixing bowl, whisk together the large eggs, liquid egg whites, sea salt, black pepper, and garlic powder until the mixture is well combined and slightly frothy.
Place the broccoli florets in a steamer basket over boiling water for 3-4 minutes until they are vibrant green and tender-crisp, then drain well.
Heat the avocado oil in an 8-inch oven-safe non-stick skillet over medium heat, swirling to coat the bottom.
Add the steamed broccoli to the skillet, spreading the florets out into an even layer.
Pour the egg mixture carefully over the broccoli, ensuring it fills all the gaps between the florets.
Sprinkle the grated sharp cheddar cheese evenly across the top of the egg mixture.
Cook on the stovetop for 2-3 minutes without stirring, just until the edges of the frittata begin to set and pull away from the sides.
Transfer the skillet to the preheated oven and bake for 10-12 minutes, or until the center is firm and the cheese has formed a golden, bubbly crust.
Remove from the oven and let it rest for 2 minutes before garnishing with chopped fresh chives and slicing into wedges.