Golden grilled cheese paired with creamy tomato soup is the ultimate vegetarian comfort food combination. This beloved family duo is a cozy, satisfying meal for chilly days.
Heat 1 tbsp olive oil in a large saucepan over medium heat. Add chopped yellow onion and cook, stirring occasionally, for 4–5 minutes until softened and fragrant.
Pour in canned diced tomatoes and vegetable broth. Stir in 1 tsp salt and 0.5 tsp black pepper. Bring to a simmer, then reduce heat to low and let cook uncovered for 15 minutes for flavors to meld.
Use an immersion blender directly in the pot to puree the soup until smooth. Stir in heavy cream, then taste and adjust seasoning as needed. Keep the soup warm over low heat, stirring occasionally.
Meanwhile, spread a thin layer of butter on one side of each slice of bread. Assemble 4 sandwiches with cheddar cheese slices between 2 buttered bread slices, buttered sides facing outward.
Heat a large skillet over medium-low. Cook sandwiches in batches for 3–4 minutes per side, pressing gently and adjusting heat so the bread crisps evenly and the cheese melts fully without burning.
Slice the grilled cheese sandwiches and serve hot alongside bowls of creamy tomato soup. For best texture, serve sandwiches immediately after grilling.