Kosher salt and freshly ground black pepper, to taste
Thinly sliced chives, for garnish
:::For the Grilled Cheese:6 slices potato bread:::
2 cups (4 ounces) grated Comté cheese
2 cups (4 ounces) grated Gouda cheese
Freshly ground black pepper, to taste
6 tablespoons unsalted butter
Make the soup: In a large pot or Dutch oven, heat the olive oil over medium-high heat. Add the onion, carrot and celery and cook until golden brown, 5 to 6 minutes. Add the chile flakes and garlic, and cook until fragrant, 1 to 2 minutes more. Pour in the crushed tomatoes and the stock. Bring the soup to a boil, then lower the heat to a simmer and cook until the liquid has slightly reduced, 20 minutes.
Using a blender, purée the soup until smooth. Return to the pot and stir in the butter until emulsified. Season with salt and pepper, then keep warm until serving.
Make the grilled cheese: On a cutting board, lay out 3 slices of bread. Divide the grated Comté and Gouda between the 3 slices and season with pepper. Top each with another slice of bread and press lightly. In a medium skillet, heat 2 tablespoons of butter over medium-high heat. Add one sandwich and top with a smaller, clean skillet to weigh it down. Cook, flipping once, until golden on both sides, 2 minutes per side. Transfer to a cutting board and slice in half diagonally. Repeat this process with the remaining 2 sandwiches.
Divide the soup between bowls and garnish with the chives. Serve immediately with the grilled cheeses on the side.