How to Make It
In a soup pot, melt the butter in the olive oil. Add the onion and garlic and cook over moderately high heat until tender, about 5 minutes. Add the paprika and cook until fragrant, about 30 seconds. Add the tomatoes, water, thyme sprig and bay leaf, season with salt and pepper and bring the tomato mixture to a boil. Cover and simmer over moderate heat until the tomatoes break down, about 15 minutes. Discard the thyme sprig and bay leaf.
Preheat the broiler. In a blender, puree the soup in batches until smooth. Strain the soup back into the pot, pressing on the solids to extract as much soup as possible. Stir the cream into the soup and season with salt and pepper.
Meanwhile, place the baguette slices on a baking sheet. Broil 6 inches from the heat until lightly toasted on both sides, about 2 minutes total. Top the toasts with the Gruyère and broil for about 30 seconds, until the cheese is bubbly. Ladle the soup into bowls and serve with the Gruyère toasts.