Canola oil

1¼ pounds ground beef (not lean)

½ cup finely chopped yellow onion

1¼ cups beef stock

¼ cup plus 2 tablespoons ketchup, plus more for serving

1 tablespoon Worcestershire sauce

½ teaspoon dried oregano

¼ teaspoon freshly grated nutmeg

Kosher salt and freshly ground black pepper

1 tablespoon flour, plus more for rolling dough

2 (14-ounce) packages frozen puff pastry dough (such as Dufour), thawed and stored in the fridge until ready to use 8 (5-inch) aluminum pie plates

1 egg