In a large pot over medium-low heat, melt 2 tablespoons of unsalted butter. Add 1 diced yellow onion and sauté until softened and translucent, about 5–6 minutes. Sprinkle in 1 teaspoon of sugar and cook until lightly browned for an additional 7–9 minutes.

Stir in 2 minced garlic cloves and cook until fragrant for 1–2 minutes. Pour in a can of San Marzano tomatoes, 2 cups of chicken stock, and 1 tablespoon of balsamic vinegar. Bring to a gentle simmer and stew for 5–6 minutes.

Transfer the soup mixture to a blender. Blend until completely smooth, then return it to the pot. Stir in ½ cup of heavy whipped cream, and season with coarse salt and freshly ground pepper to taste.

In a large skillet over low heat, melt 2 tablespoons of unsalted butter. Add 4 slices of brioche bread, toasting until golden brown, about 1.5–2 minutes per side.

Spread fig jam on two slices of toasted brioche, layer with cheddar cheese, smoked gouda, provolone, and prosciutto, then top with remaining slices of brioche.

Cook sandwiches in the skillet until golden brown and cheese has melted, approximately 1.5–2 minutes per side.

Once done, slice sandwiches into triangles and serve warm alongside a bowl of tomato soup.