Coat an 8-inch cast-iron or oven safe skillet generously with butter. Find a bowl that is about 5 inches across the top. Spray the outside with cooking spray and place it, top side down, in the center of the skillet. (You can also make a 5 inch in diameter ring with aluminum foil. Spray with cooking spray.) Place frozen dough balls around the edge of the skillet creating a ring of bread rolls. Brush dough balls with melted butter. Cover with plastic wrap and let rise for 20-30 minutes. Make Dip: In a large skillet, heat olive oil. Sauté onion until golden brown. Add fresh spinach and cook for about 4 minutes or until wilted. Remove spinach to a medium large bowl and let cool, about 15 minutes. When cooled, add cream cheese, sour cream, mayonnaise, garlic, hot sauce, 1/4 cup grated Parmesan cheese, 1/2 cup mozzarella, salt and pepper. Mix until well combined. Cover and refrigerate until ready to bake. Pre-heat oven to 375 degrees. Carefully remove bowl from center of skillet. (Bowl can be removed easier by sliding a knife or thin spatula under the bowl.) Spoon the dip mixture into the space where the bowl was, spooning right up to the edge of the dough. Bake for 20 minutes. Sprinkle remainder of parmesan and mozzarella over the top of the spinach mixture and the bread rolls. Return to oven and cook for 10 more minutes or until dip mixture bubbles and rolls are golden brown. Remove from oven. Serve hot or warm. To serve, pull apart dough pieces and dip or dunk into spinach mixture, or use a spoon mixture over pieces of bread.