Heat the olive oil in a skillet over medium heat and add the minced garlic
Sauté the garlic until fragrant and pale gold
Stir in the spinach and cook until hot and no visible liquid remains in the pan
Season the spinach with salt and pepper and remove from the heat
Brush the outer sides of the ciabatta rolls with olive oil or butter
Place the bottom halves of the rolls in a skillet over medium-low heat
Layer half of the mozzarella, feta, and parmesan onto the bottom rolls
Spread the warm spinach mixture over the cheese and sprinkle with red pepper flakes
Top with the remaining cheese and the top halves of the rolls
Place a heavy pot or cast iron press on top of the sandwiches to flatten them
Cook until the bottom is deep golden brown
Flip the sandwiches and cook the other side until deep golden brown and the cheese is melted