Cut the broccoli into florets. Discard the stalks. In a large pot of water, blanche the broccoli. Set aside. Retain the cooking water for the pasta.
In a large skillet over medium heat, saute the onion in olive oil until golden. Add the anchovies and allow to dissolve. Add the tomato puree and the broccoli florets. Cover and simmer for 15-20 minutes, until the florets begin to break apart. Add the raisins and pine nuts. Add salt and pepper to taste.
Meanwhile, add salt and return the retained cooking water to a boil. Cook the bucatini until very al dente (half of the recommended cooking time). Drain and add to the broccoli mixture.
Mix well and place in a large baking dish. Sprinkle with Parmgiano.
Meanwhile, preheat the oven to 350 degrees. Bake for 30 minutes until the top is golden brown.