Chop the basil and garlic with a knife, put in a blender, salt to taste and grind at low speed. Add tomato and ketchup. Without turning off the blender, pour in the olive oil in a thin stream, mix in the same mode until a homogeneous mass is obtained. Remove the seeds from the pepper, finely chop it. Just before serving, add the chili to the sauce and stir. Sprinkle with grated parmesan.