Preheat the oven broiler to high. Wash and slice the sweet red peppers in half, removing the seeds. Place them skin-side up on a baking sheet lined with foil. Broil the peppers for about 5 minutes, or until the skins are blistered and charred.

Once roasted, transfer the blistered peppers to a bowl and cover tightly with plastic wrap. Allow them to steam for 20 minutes.

While the peppers are steaming, preheat the oven to 400°F (200°C). Wash and trim the cauliflower into florets, then toss with 2 tablespoons of olive oil. Spread the florets on a baking sheet and roast for 25-30 minutes, until tender and golden brown.

Heat the remaining 2 tablespoons of olive oil in a large stockpot over medium heat. Add the chopped onion and sauté for 6-8 minutes until golden and soft. Stir in the minced garlic, rosemary, and paprika, cooking for an additional minute.

Sprinkle in the flour, stirring constantly for about a minute. Gradually pour in 4 cups of chicken stock, stirring continuously until the mixture comes to a gentle boil.

Peel the skins from the roasted peppers. Add the roasted cauliflower florets and chopped peppers into the stockpot. Using an immersion blender, puree the mixture until completely smooth.

Stir in 1 cup of milk, seasoning with salt, pepper, and cayenne pepper to taste. Heat gently until warmed through, but do not let it boil.