Wash broccoli, cut into florets, and place in a microwave-safe bowl with 1/4 cup water. Cover with plastic wrap and microwave for 2 minutes until broccoli is bright green and steamed. Finely chop broccoli.
Heat a pan over medium heat with extra virgin olive oil. Once heated, add garlic and cook for about 30 seconds until fragrant. Add in broccoli, pecorino romano, and black pepper. Stir and cook for about 1-2 minutes until it smells delish then remove from the pan and set aside.
Take your bread and spread the mayo on one side of each slice, make sure you spread it evenly and all the way to the edge. In a non-stick pan on medium heat, place your bread in, mayo slide down. Layer cheddar cheese, or pepper jack, on both slices and cover to melt. Tip: Add a few drops of water to the pan to create steam to help the cheese melt.
Once melted and the bread is golden brown, add your broccoli mixture to one slice of bread and cover with the other. Remove from the pan and cut, diagonally, of course.