Cook Sausage: In a large skillet over medium-high heat, cook the sausage until browned and crispy, about 5-7 minutes.

Make Gravy: Sprinkle flour over cooked sausage, stir and cook for 1 minute. Gradually whisk in milk and cook until thickened, about 3-5 minutes.

Scramble Eggs: In a separate skillet, scramble eggs over medium heat until fluffy, about 3-4 minutes. Remove from heat.

Prepare Dough: Preheat oven to 375°F (190°C). Combine flour and salt. Cut in shortening and butter until crumbly.

Bring Dough Together: Whisk egg, vinegar, and cold water. Gradually mix into flour until dough forms. Refrigerate if needed.

Roll Dough: Divide dough, roll to ⅛-inch thickness, and cut into rectangles of 3x4 inches.

Assemble Pop-Tarts: On baking sheets, place half of the rectangles, brush edges with egg wash, add filling, and top with another rectangle.

Bake: Brush tops with egg wash and bake for 25 minutes until golden brown.

Cool: Let pop-tarts cool on the baking sheet for about 5 minutes.