Frico-Crusted Grilled Cheese With Arugula Pesto

Place the garlic through lemon zest and juice in a food processor and pulse to a grainy homogenous consistency. With the processor running, slowly drizzle in the olive oil until the pesto takes on a creamy consistency and falls away from the sides of the processor bowl. Stir in the Parmesan by hand. Add salt and pepper to taste.
Heat a non-stick skillet over medium heat. Place 1/3 cup of Parmesan in a thin layer, roughly the shape of your sandwich bread and let cook until melted, bubbly, and just starting to brown, about 3 minutes.
Place a slice of bread atop the melted Parmesan, pressing down slightly, and build the grilled cheese in the skillet: place 2 slices of fontina atop the bread and spread with 1 tablespoon of pesto. Top with a 2nd slice of bread. Cook about an additional 3 minutes before turning out of the skillet (you need to melt more Parmesan before flipping to cook the other side of the sandwich). Repeat the Parmesan melting with another 1/3 cup of cheese in the skillet. Once slightly brown, place the sandwich back in the skillet to cook the other side atop the Parmesan, another 3 minutes or so. Weighing down the sandwich with a heavy cast iron skillet will promote even cooking, browning and melting, and is recommended if you have the equipment.
If you have a large enough non-stick skillet, you can make 2 sandwiches at once. If not (like me), repeat the process to make a second sandwich while keeping the first warm on a baking sheet in a 200F oven. Enjoy!