Melt the butter in a large skillet over medium heat until foaming. Add the finely chopped onion and diced celery and cook, stirring occasionally, until softened and translucent, about 4–6 minutes. Do not brown.

Make a roux

Sprinkle the all-purpose flour evenly over the softened vegetables and stir constantly for 1–2 minutes to cook the flour and remove the raw taste. The mixture should be bubbly but not darken significantly.

Add liquids

Slowly whisk in the chicken or turkey stock until smooth, scraping any browned bits from the pan. Then whisk in the whole milk and heavy cream until the sauce is uniform. Bring the mixture to a gentle simmer; it will thicken as it heats, about 3–5 minutes.

Finish the gravy

Stir in the shredded cooked turkey. Add the thyme, Worcestershire sauce (if using), salt, and black pepper. Reduce the heat to low and simmer gently for 4–6 minutes to heat the turkey through and meld flavors. Taste and adjust seasoning with additional salt and pepper as needed.

Adjust consistency

If the creamed turkey is too thick, thin with up to 2 tablespoons of milk or stock until desired consistency is reached. If too thin, cook a couple more minutes to reduce. Stir in the chopped parsley just before serving.

To Serve

Warm the biscuits: If your homemade biscuits are not warm, preheat oven to 350°F (175°C) and place split biscuits on a baking sheet, brush cut sides with the melted butter, and warm for 5–8 minutes until heated through.

Assemble: Place one warm biscuit half on each plate, spoon generous portions (about 1/2 to 3/4 cup) of the creamed turkey over the split biscuit, and top with the other half if you like or serve open-faced. Sprinkle extra black pepper and a little chopped parsley.

Serve immediately: Serve hot so the gravy is saucy and biscuits remain tender. Leftovers: store cooled creamed turkey in an airtight container in the refrigerator for up to 3 days; reheat gently over low heat, thinning with a splash of milk or stock.