Step 1

Preheat oven to 400 F.

Step 2

Place broccoli florets on a large half sheet baking pan. Drizzle with olive oil, salt, and pepper, and toss to combine. Roast in the oven for 12-15 minutes, or until lightly browned and tender. Set aside.

Step 3

Spread 1/2 tablespoon of butter on each of 4 slices of bread and place them on a plate with the butter side facing down.

Step 4

Divide cheddar cheese equally onto 2 of the slices. Top those same 2 slices with an even layer of roasted broccoli, a few slices of roasted red peppers, and shredded mozzarella. Top each with the remaining slice of bread (butter side on top).

Step 5

Heat a large skillet or griddle pan over medium heat until it's hot, about 2 minutes. Add the sandwiches and cook for 3-5 minutes, until golden brown. Note that it helps to place something heavy on top to disperse the weight evenly (I use a large cast-iron skillet to press down on the sandwiches). Flip sandwiches and cook without any weight on top for another 2-3 minutes, until just browned.

Step 6

Slice in half, drizzle with balsamic vinegar reduction (if using), and serve immediately.