This rich sauce is perfectly balanced by fresh, light seafood.
Heat a large nonstick skillet over medium to medium-high.
Melt the butter in the skillet. When it foams, add the shallots and garlic and stir for 1 to 2 minutes.
Sprinkle the flour into the skillet. Whisk in the flour, let the mixture bubble, then whisk in the sherry until it’s incorporated into the sauce, about 30 seconds. While whisking, slowly stream in the half-and-half. Reduce the heat to low and bring the sauce to a low simmer. Season the sauce with nutmeg, salt, and white pepper. Remove from heat. Cover to keep warm while you cook the seafood.
In another large nonstick skillet, heat the oil, three turns of the pan, over medium-high to high. Add the seafood and cook until lightly browned on the outside and opaque inside, 5 to 7 minutes. Season with salt, then douse the seafood with the lemon juice. Transfer the seafood to the sauce, folding gently to combine.
Transfer to a serving bowl or platter. Top with the herbs and a light sprinkling of paprika, if using. Serve with the bread.