Melt 1 tablespoon butter in same skillet over medium heat. Add shallots, mushrooms and peas; sauté for about 5 minutes until cooked. Stir the risotto into the shallot, mushrooms and peas; stir to coat, about 2 minutes. Add 2 cups broth mixture from the medium pot. Simmer until liquid is absorbed, stirring often. Continue adding broth mixture 1 cup at a time, stirring often and simmering until liquid is absorbed before adding more, about 15 minutes until it’s all gone. Pour the risotto mixture back into the medium pot and stir in reserved shrimp cooking liquid, lemon zest and warmed half and half. Cook until risotto is just tender and mixture is creamy, about 10 minutes longer.