As the corn is roasting, prepare the shrimp broth. In a soup pot, melt the butter over medium heat. Once melted and frothy, add the shrimp shells and crushed red pepper. Cook, lightly mashing the shells against the side of the pot occasionally, for 10 minutes until fragrant. Add the chicken stock and bring to a boil. Reduce heat and simmer, uncovered, for 15 minutes to allow the shrimp flavor to infuse the chicken stock.