Preheat your oven to 400°F (200°C) and line a muffin tin with paper liners or grease it lightly. Roll out your cold puff pastry on a floured surface until it's about 1/4 inch thick. Cut the rolled pastry into squares that are approximately 4 inches on each side.

Take each pastry square and place your desired filling directly in the center. Gently fold the corners of the square inward towards the center to encase the filling, sealing edges tightly.

Roll each filled pastry square into a compact cylinder and bend it into a U-shape, nestling it into the muffin tin.

In a deep frying pan, pour enough neutral oil to submerge the cruffins and heat to 350°F (175°C). Monitor the oil temperature closely.

Once the oil has reached the desired temperature, carefully lower each cruffin into the hot oil, frying for about 3-4 minutes on each side until golden brown.

Remove the cruffins from the oil and let them drain on paper towels. Toss them in a mixture of cinnamon and sugar immediately while warm.

Serve your Churro Cruffins warm, straight from the fryer for the best flavor experience.