How to Make It
Preheat the oven to 425°. Lightly oil an 8-by-11 1/2-inch or 9-by-13-inch baking dish. In a medium saucepan, bring the chicken stock and 2 cups of water to a boil. Add 1 teaspoon of salt. Gradually whisk in the cornmeal until smooth. Cook over moderate heat, stirring with a wooden spoon, until thickened, about 10 minutes. Pour the polenta into the baking dish and smooth the top; brush with 1 tablespoon of olive oil. Bake for 1 hour and 15 minutes, until the top and bottom are golden and crusty.
Meanwhile, in a large, deep skillet, heat the remaining 3 tablespoons of olive oil until shimmering. Add the pancetta and cook over moderately high heat until golden, 4 to 5 minutes. Add the onion, garlic and crushed red pepper and cook until the onion softens. Add the broccoli rabe and the remaining 1/4 cup of water, season with salt and pepper and toss gently. Cover and cook until softened, 5 minutes. Uncover and cook, stirring occasionally, until the water has evaporated and the broccoli rabe is tender, 2 minutes longer.
Cut the polenta into 6 pieces and transfer to plates. Stir half of the Pecorino into the broccoli rabe and spoon it over the polenta. Sprinkle with the remaining Pecorino and serve.