Preheat the oven to 325 degrees F. Grease inside cups of a 12 muffin pan with some drops of oil and use a paper towel to spread it. Make sure both bottoms and sides get oiled. Set aside.
Chop broccoli into florets and boil them in boiling water (or microwave broccoli) for 5 to 7 minutes or until they are fork tender. Chop them into small pieces. Set aside. Saute sliced mushroom in a skillet with a tbsp of olive oil until tender.
Add minced garlic and saute for 1 added minute. Remove from heat and set aside. Place eggs into a medium sized bowl and whisk.
Add salt, black pepper, and baking powder. Whisk to combine. Fold in chopped broccoli, sauteed mushroom and shredded cheese. Stir to combine.
Divide the egg mixture into 12 muffin molds evenly. Bake egg muffins for 25 to 30 minutes, or until nicely golden on top.
Use a knife around the edges to loosen and scoop out with a tbsp on to plates to eat.