Place whole head of cauliflower in a large pot. It should fit comfortably, with 1 to 2 inches of room left on all sides. Remove and set aside.
Add the can of tomatoes one tomato at a time squishing each one over the cauliflower in your hand so as to make it sort of chopped., then add parsley stalks, chili powder, smoked paprika, onion powder, and freshly ground pepper. Bring to sauce to a simmer over medium heat.
Stir in anchovies, olives, and red-wine vinegar, then bring to a low boil.
Gently push whole head of cauliflower down into the sauce. (Sauce should come halfway up the sides of the cauliflower). Drizzle with olive oil, a little salt and cover.
Let cook over low heat for 45 minutes. To serve, garnish with chopped parsley. You should be able to literally scoop up servings in a big spoon.