Heat vegetable oil in a medium saucepan over medium heat. Add chopped onions and bell peppers, and sauté until softened.

Add ground meat or plant-based protein. Cook until browned and fully cooked through. Stir in ketchup, mustard, and shredded cheese until well mixed.

Roll out vegan puff pastry on a lightly floured surface. Use a ghost cookie cutter to cut out shapes.

Spoon 1-2 teaspoons of filling onto half of the ghost cutouts. Brush edges with non-dairy milk and place the other cutouts on top, sealing the edges with a fork.

Chill the assembled pies in the refrigerator for 30 minutes to 1 hour to firm up.

Preheat your oven to 400 degrees F. Brush the tops of the ghost pies with non-dairy milk and sprinkle with course sugar, if desired.

Bake for 15-20 minutes, rotating pans halfway through, until golden brown and flaky.

Remove from the oven and let cool slightly before serving.