In a heavy skillet over medium-high heat, crumble and brown the bulk breakfast sausage until fully cooked and golden brown.

If sausage is lean or you prefer richer gravy, stir in 2–3 tablespoons unsalted butter until melted.

Sprinkle 1/4 cup all-purpose flour evenly over the sausage and drippings. Stir continuously for about 1 minute to cook the flour.

Gradually pour in about 1/2 cup of the whole milk while whisking constantly to avoid lumps.

Continue whisking as you add the remaining milk in two or three additions until the mixture is smooth.

Reduce heat to medium-low and simmer, stirring occasionally, for about 5–7 minutes, until gravy thickens and coats the back of a spoon.

Season with 1/2 teaspoon salt and 1/4 teaspoon freshly ground black pepper. Stir in a pinch of cayenne pepper or red pepper flakes if using.

Remove from heat, spoon gravy over warm biscuits, toast, or potatoes. Garnish with chopped parsley or chives and serve immediately.