Preheat oven to 425° F. Line 2 baking sheets with parchment paper and set aside. Whisk together one egg and one tablespoon of water to create an egg wash, and set aside.
Beat remaining egg in a large bowl until frothy. Add the sausage, breadcrumbs, garlic, onion, parsley, black pepper, and mustard. Mix until thoroughly combined.
Unwrap the package of puff pastry and place one puff pastry sheet on a floured surface. Roll out dough with a rolling pin to even out dough and deep creases.
Divide sausage mixture into 6 equal portions. Place the sausage log along the long edge of the pastry sheet and roll the pastry over the sausage, enclosing it completely. Seal the edge by pressing it down or using a bit of beaten egg wash as glue.
Cut the long sausage roll into smaller, bite-sized pieces. You can make them as large or as small as you prefer. Six, 2-inch pieces is a good size.
Cut vent holes into the center of each sausage roll with the tip of a sharp knife. Place in a single layer on prepared baking tray, seam side down. Brush with remaining egg wash.
Place in preheated oven and bake for 15 to 20 minutes, or until the pastry is puffed and golden, and the sausage is cooked through. All oven cook differently, your baking time may be different.
While the first pan is baking, follow the same process with the remaining sausage and pastry. Allow to cool slightly and serve while warm or at room temperature.
Notes
To store leftover Sausage Rolls: Allow the sausage rolls to cool to room temperature before storing. Place them in an airtight container and store in the refrigerator for up to 3 days.
To reheat: Remove sausage rolls from the refrigerator and place into a preheated 350° F. oven or air fryer and reheat just until heated through, about 10 to 15 minutes.
HP Sauce is the traditional dipping sauce for sausage rolls in Britain. It can be found on Amazon, in the International aisle in larger grocery stores, or at Cost Plus World Market.
See original post for complete list of serving suggestions and make ahead directions.