In a mixing bowl, combine all-purpose flour, salt, sugar, and baking powder. Cut in the cold, cubed butter until the mixture is crumbly like coarse sand. Add milk and the egg slowly, combining until just mixed. Chill the dough in the refrigerator for about 30 minutes.

In a skillet, scramble the eggs until just set, and cook the breakfast sausage until browned and cooked through. Combine them in a bowl, adding in the shredded cheese and optional Dijon mustard for a kick!

On a lightly floured surface, roll out the chilled dough to about ¼ inch thick. Cut the dough into rectangles, approximately 4x6 inches, to create your hot pockets.

Place 2-3 tablespoons of your delightful filling in the center of each rectangle. Fold the dough over to create a pocket, then seal the edges tightly using a fork for that perfect homemade touch.

Preheat your oven to 400°F (200°C). Brush the tops of the hot pockets with the beaten egg for a beautiful golden finish. Bake for 20-25 minutes until they are puffed and evenly golden brown, then allow them to cool slightly before serving.