How to Make It
Heat broiler. Melt 4 tablespoons butter in a large skillet over medium-high heat. Add the shallot and cook 1 to 2 minutes, until just starting to brown.
Sprinkle the flour over the shallot and butter and whisk until smooth. Reduce heat to medium.
Add half-and-half slowly, whisking into a smooth sauce. Cook 2 to 3 minutes, until thickened, whisking as needed. Add the sugar and stir.
Add the spinach, nutmeg, and 1 teaspoon each salt and pepper and cook, stirring occasionally, until hot. Reduce heat to low so the spinach stays warm.
On a cooking spray-coated broiler pan, place the fillets, top evenly with lemon juice and bread crumbs, and dot with the remaining 2 tablespoons butter. Broil 5 to 6 minutes or until the fillets are opaque and the bread crumbs golden.
Spoon some creamed spinach onto each of 4 plates, then place a fillet on top. Serve with the lemon wedges.