1. Preheat the oven to 400°.
2. Making the filling: Cut the sausage in half lengthwise; cut cross- wise into 1/4-inch-thick slices. Combine the sausage, onion, and garlic in a 12-inch cast iron skillet; cook over medium-high heat until the sausage is browned and the onion is softened, stirring occasionally. Add the black-eyed peas, broth, greens, and hot pepper sauce; mix well. Bring to a boil. Reduce the heat to low and simmer 10 minutes.
3. Make the topping: Combine the topping ingredients in a large bowl, stirring until blended. Pour the batter just around the edge of the sausage mixture in the skillet. Bake until the topping is golden brown, 30 to 35 minutes.
4. Serve with desired garnishes.
Optional garnishes: Sour cream, pickeled jalapeño chile slices, and/or fresh parsley or cilantro leaves.