Place oven rack at the highest setting. Pre-heat oven to 400 degrees. Massage broccoli with melted butter, lemon juice, sea salt and black pepper.
Spread evenly in single layer on baking sheet and roast until it starts to brown (15 min) then flip them over and cook for five more min.
Sweat the Celery: While Broccoli is roasting, sweat celery with salt, pepper, butter, and lemon juice in a pan over a low flame until translucent (10 min).
Frittata: Turn on the broiler. Heat skillet over a medium high flame. In a mixing bowl whisk the eggs, add in 2/3rds of the vegetables. Transfer mixture to the hot skillet.
Cook on the stove-top until only the top of the eggs are runny and the bottoms are set. Place under the broiler until the top of the frittata starts to brown (4-5 min).
Using a spatula remove the frittata onto a plate. Using a pizza cutter slice into 8 wedges.