►Preheat oven to 400°F. Bring a large pot of water to boil and salt generously.
► Add pasta and cook to al dente according to package directions. When there is one minute of cooking time remaining, scoop out about ½ cup pasta water and set aside. Then add the broccoli rabe to the pot with the pasta, allowing it to blanch for 1 minute, before draining everything
carefully into a colander. Set aside.
►Return empty pot to stovetop and over medium heat, melt butter and add grated garlic, stirring frequently. Don’t let it brown. When it starts to sizzle, add black pepper and let it cook for 30 seconds. Add pasta water, bring mixture to a boil, then add the cream, lowering the heat a bit and allowing mixture to simmer for 3 minutes.
►Lower heat to a low flame, add cooked pasta and broccoli rabe with chili flakes, and then fold in half of Roquefort and lemon zest. Stir constantly for about 3 minutes, allowing sauce to thicken and cheese to melt fully.
►Transfer to a 9-inch round baking dish (9-inch square works, too), top with remaining Roquefort, and transfer to oven, baking until bubbling, about 10 minutes. Then broil for just a minute or two to caramelize the top, keeping an eye on it. Serve right away.