Combine the mayonnaise, garlic and gorgonzola cheese in a small bowl. Slice the rolls in half lengthwise and spread about 1 tablespoon of the mayonnaise mixture on each half of the rolls.
Place a slice of fontina cheese on the bottom half of each roll and arrange a layer of roasted red peppers on top.
Add 3 to 4 slices (about 3 ounces) of roast beef, a layer of fresh spinach leaves and another slice of fontina.
Place the other half of the roll on top and press down firmly.
Heat a grill pan over medium heat and brush the tops of the sandwiches lightly with olive oil. Arrange the sandwiches, top side down, in the preheated pan and weigh them down with a sandwich press or foil covered brick.
Cook until the cheese has melted and the bread is lightly toasted, 1-1/2 to 2 minutes. Flip the sandwiches over, weigh them down again and cook for an additional 1-1/2 to 2 minutes. Repeat with remaining sandwiches if necessary.
Cut each sandwich in half diagonally and serve immediately.
Depending on the size of your pan, you may need to work in 2 batches.