In a skillet over medium heat, brown your breakfast sausage for about 5-7 minutes until crispy and cooked through. Stir in a couple of tablespoons of flour and let it cook for an additional minute, then slowly whisk in one cup of whole milk. Cook, stirring frequently, until thickened and bubbly, about 3-4 minutes. Season with seasoned salt and black pepper to taste, then set aside to cool slightly.

In a separate bowl, crack and scramble 4 large eggs, cooking them in a non-stick skillet over medium heat for about 3-5 minutes until just set but still soft. Stir gently to avoid overcooking. Once done, remove from heat and let the scrambled eggs cool on a plate while you prepare the pastry dough.

In a large mixing bowl, combine 2 cups of all-purpose flour with ½ teaspoon of seasoned salt. Start cutting in ½ cup of vegetable shortening and ½ cup of cold butter until the mixture resembles coarse crumbs. In a small bowl, whisk together one large egg with a tablespoon of vinegar and enough cold water to make a total of 1/3 cup. Stir this mixture into the flour until just combined; form the dough into a ball and chill in the refrigerator for 30 minutes.

Preheat your oven to 375°F (190°C). On a floured surface, roll out the chilled dough to about ¼ inch thick. Use a sharp knife or pizza cutter to cut rectangles measuring approximately 3x4 inches. You'll need two rectangles for each Savory Breakfast Pop-Tart. Place the cut pieces on a parchment-lined baking sheet.

Take one rectangle and place it on the baking sheet. Brush the edges lightly with a beaten egg wash to help seal. Spoon a generous amount of your cooled sausage gravy followed by a layer of scrambled eggs and a sprinkle of shredded cheese onto the center. Carefully place the second rectangle on top, crimping the edges with a fork to seal them securely.

Brush the tops of each assembled Savory Breakfast Pop-Tart with more egg wash. Bake in your preheated oven for 25 minutes, or until they're puffed and golden brown. Once done, remove them from the oven and allow to cool for just a few minutes before serving.