Make the dough: Combine cold flour and 1/4 of the cold butter cubes in a food processor. Pulse until mixture resembles coarse meal. Add remaining butter cubes and pulse until pea-sized pieces remain. Add cold water in a steady stream and process evenly until a loose, ragged dough forms.
Place dough between two sheets of waxed paper. Roll dough into a rectangle, then cut into three strips.
Make the filling: Mix pork sausage, bread crumbs, one egg, garlic, and onion powder together in a bowl until well combined. Place 1/3 of the filling in a strip onto each piece of dough; roll dough around filling into a log. Refrigerate logs for 30 minutes.
Preheat the oven to 425 degrees F (220 degrees C). Beat remaining egg in a small bowl.
Cut logs into 1-inch pieces. Place pieces, seam-side down, onto a baking sheet, and brush with egg.
Bake in the preheated oven until golden brown, 15 to 20 minutes.