Preheat oven to 200°C (400°F) and line a baking tray with parchment paper.
Heat olive oil in a pan, sauté garlic, onion, celery, and bacon until softened. Let cool.
In a bowl, mix pork mince, breadcrumbs, egg, salt, pepper, fennel seeds, and sautéed ingredients.
Cut puff pastry sheets into halves and place a strip of filling along the edge of each piece.
Roll the pastry over the filling, sealing the edges with whisked egg. Slice into desired sizes.
Place on a baking tray, brush the tops with egg wash, and bake for 25 minutes until golden brown.
Let cool slightly before serving with ketchup or your favorite dip.