In a medium skillet over medium heat, cook breakfast sausage until browned, about 5–7 minutes. Stir in flour and cook for 1–2 minutes. Gradually whisk in milk and season with salt and pepper, cooking until thickened.

In a large skillet on medium-low heat, scramble eggs, cooking for about 3–4 minutes until desired doneness. Set aside.

In a large bowl, combine flour and salt. Cut in butter until crumbly. Mix in egg wash and vinegar until a dough forms. Chill for 30 minutes.

Roll out the dough to ⅛-inch thickness and cut into rectangles for pop-tarts.

Assemble by placing sausage gravy and scrambled eggs onto half of the dough rectangles, add cheese if desired, and top with remaining rectangles. Seal edges.

Preheat oven to 375°F (190°C). Brush tops with egg wash and bake for 25 minutes or until golden brown.

Allow to cool for 10 minutes before serving.