Adapted from Brassicas—Cooking the world’s healthiest vegetables
Preheat the oven to 400°F. Put the oil and garlic in a 10-12 inch non-stick frying pan and place over medium heat. When the garlic starts to sizzle, add the broccoli, stir to coat it with the oil, and cook for about 2 minutes. Stir in ¼ teaspoon of the salt and the water and cook, stirring occasionally, for about 5 minutes, until the broccoli is tender.
Meanwhile, in a bowl, beat the eggs with the remaining ½ tsp salt and the pepper until blended. When the broccoli is ready, sprinkle the cheese evenly over it and then add the eggs to the pan. Cook for about 2 minutes, until the eggs are set around the edges.
Transfer the pan to the oven and bake for 8-10 minutes, until the eggs are just set. A knife inserted into the frittata should come out clean. Remove from the oven and carefully slide the frittata out onto a serving plate.