Melt the butter over medium heat in a 10 inch non stick skillet. Once butter starts foaming, add the asparagus and cook for 2 minutes. Season with sea salt and fresh ground pepper. Add the leeks and cook for an additional 2 minutes. Add the cherry tomatoes and cook for one more minute.
Whisk the salt and pepper into the beaten eggs. Reduce heat to medium low. Add the eggs and cheese to the skillet, folding gently to incorporate. Cover and cook for 3 minutes or until the eggs are starting to set but still wet on the top.
Preheat the broiler. Top the frittata with the extra ¼ cup of cheese. Place under the broiler for 2-3 minutes or until top is golden brown.
Let the frittata rest for 5 minutes. With a spatula, gently release the eggs from the pan along the sides and bottom. Gently tip pan to allow frittata to slide out of the pan onto a platter. Or, cut into wedges and serve directly out of the pan.