Step 1

For the tomato soup: Heat a large saucepan over medium heat and add the oil. When hot, add the onion and a large pinch of salt and cook until starting to soften, about 2 minutes. Add the garlic and cook for an additional minute. Mix in the tomatoes and chicken stock. Add the cream, hot sauce and oregano if using and bring to a simmer. Simmer until thickened and the flavors come together, 20 to 30 minutes. Taste and season with additional salt if needed. Let cool slightly, then transfer to a blender and puree until smooth.

Step 2

For the grilled cheese: Heat a large skillet or griddle over medium heat.

Step 3

Spread the mayonnaise or melted butter on one side of each slice of bread. Sprinkle the Parmesan over the mayonnaise or butter. Flip the slices and put 4 pieces of Cheddar on 4 of the bread slices. Spread the other bread slices with mustard, if using, and close the slices together to form sandwiches (the mayonnaise and Parmesan should be on the outside).

Step 4

Working in batches if necessary, transfer the sandwiches to the skillet and cook until browned and toasted, 2 to 3 minutes per side. Slice and serve with the tomato soup.u00A0