Heat oven to 450°F. Line a rimmed baking sheet with foil. Place a strainer over a large bowl, and open the first can of tomatoes into it. With your fingers, carefully open whole tomatoes and push out seeds, allowing juices to fall through the strainer into the bowl. Spread seeded tomatoes in a single layer on the foil. Repeat with the second can of tomatoes. Sprinkle tomatoes on the roasting pan evenly with brown sugar. Bake until all liquid has evaporated and tomatoes begin to color, about 30 minutes. Let tomatoes cool slightly while you work on the rest of the soup.

Heat butter over medium heat in a large saucepan until foaming. Add shallots, tomato paste and allspice. Reduce heat to low, cover, and cook, stirring occasionally, until shallots are softened, about 7 to 10 minutes. Add flour and cook, stirring constantly, until thoroughly combined, about 30 seconds. Gradually add vegetable or chicken stock, whisking constantly to combine; stir in reserved tomato juice.

Gently peel roasted tomatoes from the foil and add them to the pot. Cover, increase heat to medium, and bring to a boil. Reduce heat to low and simmer, stirring occasionally, to blend flavors, about 10 minutes.

Off the heat, use an immersion blender to puree the soup until smooth. Add cream — start with just 1/4 cup, adding the last 1/4 cup if desired, drizzled over serving bowls — warm over low heat until hot, about 3 minutes.

Off heat, stir in brandy and season with salt and cayenne. Serve immediately.

Soup can be refrigerated in an airtight container for up to 2 days. Warm over low heat until hot; do not boil.