Steam or Blanch the Broccoli: fill a pot with about 4 inches of water. Bring the water to a boil over high heat. Once boiling, place the broccoli florets in. Steam the broccoli for about 4 - 6 minutes, or until it is tender but still bright green. You can test doneness by piercing a floret with a fork; it should be tender but not mushy. Then drain.

Shock the Broccoli: Immediately transfer the broccoli to a bowl of ice water to stop the cooking process. Let it cool in the ice water for the same amount of time it was in the boiling water (2 - 3 minutes). Remove the broccoli from the ice water and drain well. Pat dry with a paper towel if needed.

Heat olive oil in a non-stick skillet over medium heat. Add the sausage and break up into smaller pieces until browned and no longer pink.

Add the mushrooms and cook for about 3 - 4 minutes, until they start to soften.

Add the broccoli to the skillet. Cook for another 2 minutes until heated through.

Pour the egg into the skillet, tilting the pan to spread it evenly. Season with salt and pepper to taste.

Cook for about 2 - 3 minutes, or until the eggs are mostly set. Add the cheese and gently fold the omelet in half and cook for another 1 - 2 minutes.