Procedure

To Make the Soup:

Preheat the oven to 400° F and line a rimmed sheet pan with parchment paper.

Cut the entire head of garlic in half horizontally and drizzle 1-2 tsp of olive oil over both sides. Wrap both halves of garlic tightly in aluminum foil. Toss tomatoes, onions, and cauliflower with the rest of the olive oil and 1/2 tsp kosher salt and then spread them in an even layer on the prepared sheet pan. Place the wrapped garlic on the sheet pan with the vegetables and roast for 30-35 minutes, until vegetables are soft and beginning to brown and garlic is soft and golden. Let cool.

When the vegetables reach room temperature, transfer them to a blender. Squeeze the roasted garlic out of it’s skins and into the blender. Add tomato sauce and water or stock and blend on high speed until smooth.

Transfer soup to a large pot, add basil, salt and pepper to taste, and bring to a simmer over medium heat, stirring occasionally. Simmer for 20-25 minutes, until hot and flavors have melded, then stir in butter, and cook until melted. Serve soup hot, drizzled with spiced chili oil.

To make the Spiced Chili Oil:

Heat a small skillet over medium heat. When the pan is hot, add fennel seeds, cumin seeds, and chili flakes. Toast for 1-2 minutes, just until fragrant and beginning to brown, taking care not to burn them. Immediately transfer to a bowl and add olive and salt. Drizzle over roasted tomato soup.