This grilled cheese with tomato is one of the best grilled cheese recipes out there, featuring roasted tomatoes, tomato mayo, basil, and melty mozzarella.
Line a baking sheet with parchment paper and place the tomatoes on the sheet. Roast for 15 minutes until the tomatoes are starting to burst.
Place the tomatoes in a bowl and carefully mash with a potato masher to extract the juice. Strain the tomatoes completely and reserve the juice in a small bowl. Mix 1 tablespoon of the juice into ¼ cup mayonnaise until it has the consistency of a sauce (double the tomato juice and mayonnaise for extra sauce). Reserve the strained tomatoes and sprinkle them with kosher salt.
Spread each slice of bread with tomato mayo. Top with 1/4 of the strained tomatoes, shredded mozzarella, and some torn pieces of basil. Sprinkle the toppings with a pinch of kosher salt and top with another slice of bread.
Heat a grill pan to medium high and brush it with butter. Cook the sandwiches until toasty and the cheese is melted, about 3 minutes per side. Serve immediately.