Step 1

Heat a large skillet over medium heat. Add the oil, garlic, red pepper flakes and 1/4 teaspoon salt. Cook stirring often, for 2 minutes or until fragrant and the garlic is just beginning to brown. Add the spinach and remaining salt and cook an additional 2 minutes or until the spinach is wilted. Drain in a strainer squeezing out any excess liquid. Allow to cool slightly for about 5 minutes or until cool enough to handle. Roughly chop the spinach and set aside. Wipe out the pan with a paper towel and set aside.

Step 2

Lay out 4 slices of bread. Sprinkle each slice of bread with 1/2 cup mozzarella cheese. Divide the spinach evenly over the slices. Place the remaining slices of bread on top. Spread the top slices of bread evenly with half of the butter or mayonnaise. Sprinkle each buttered sandwich with 1 tablespoon parmesan cheese.

Step 3

Heat the large skillet over medium low heat. Add the sandwiches to the hot pan, butter and cheese side down. You may have to do this in two batches. Cover the sandwiches with a lid slightly smaller than the pan so you can press down on the sandwiches. Allow to cook for 3 to 4 minutes or until golden brown and crispy and the mozzarella is beginning to melt. Remove the lid and butter and cheese the top pieces of bread. Flip the sandwiches and cook an additional 3 minutes or until the bread is golden brown and crispy and the cheese is melted. Remove from the pan and allow to sit for 3 minutes before slicing in half and serving warm. Continue with remaining sandwiches if cooking in batches.