I got this recipe from my mother-in-law. It's a childhood favorite of my husband.
Standard pan-fried poultry rely on simple pan juices thickened with water or stock, whereas this preparation utilizes a complex emulsion of butter, flour, and acidic catalysts. When flour is whisked directly into the residual 1/2 cup of melted butter after searing the split bird for 20 minutes, it forms a traditional blond roux that prevents the fats from separating during subsequent liquid additions. Maintaining a steady medium heat ensures the starch molecules swell properly without scorching the dairy solids.
The sauce achieves its characteristic pungency through the interaction between 1 1/2 teaspoons of dried mustard, Worcestershire sauce, and ketchup, which introduce acetic acid, umami compounds, and natural sugars that balance the high fat content of the 4-pound poultry. Incorporating 1 cup of dry sherry near the end of the stovetop phase introduces ethanol-soluble flavor congeners that evaporate partially during the final 15 to 20 minutes of high-heat baking at standard oven temperatures, leaving behind a concentrated, aromatic residue that clings to the skin. Letting the casserole rest off the heat allows the starches to fully set the sauce viscosity to a coating consistency.
Refrigerating leftovers within two hours of baking concentrates the sherry and Worcestershire notes further as the animal fats solidify. Reheating individual portions gently with a splash of chicken broth restores the fluid emulsion without breaking the butterfat.