01 -
Set the oven to 400°F.
02 -
In a large skillet over medium heat, crumble and cook the breakfast sausage until it is fully browned and no longer pink, about 6 to 8 minutes. Drain excess fat, leaving a small amount for flavor.
03 -
Stir in unsalted butter and let it melt. Sprinkle the flour into the pan, whisking to incorporate, and cook for 1 minute to form a roux.
04 -
Slowly pour in whole milk while whisking to prevent lumps. Cook, stirring frequently, until the mixture thickens to a rich, creamy gravy, about 3 to 5 minutes.
05 -
Add kosher salt and black pepper to the gravy. Mix until evenly distributed.
06 -
If needed, gently roll the thawed puff pastry to fit a 9-inch pie dish. Lay the pastry into the dish so the edges come up the sides.
07 -
Pour the hot sausage gravy evenly into the pastry-lined pie dish.
08 -
Trim any overhanging pastry dough and crimp or fold edges as desired.
09 -
Whisk together the egg and 1 tablespoon water in a bowl. Brush the mixture onto the edges and top of the pastry as desired.
10 -
Place in the preheated oven and bake for 20 to 25 minutes, or until the pastry is puffed and golden brown.
11 -
Allow the pie to rest a few minutes before slicing. Garnish with chopped parsley if desired and serve warm.