Step 1: Prepare the Puff Pastry
Preheat your oven to 375°F (190°C).
Roll out the puff pastry on a lightly floured surface into a thin rectangle.
Brush the entire sheet with melted butter.
Mix the granulated sugar and cinnamon together in a small bowl, then sprinkle evenly over the pastry.
Step 2: Roll and Shape
Roll the pastry tightly into a log, then cut it into 6–8 equal pieces.
Place each piece, cut side up, into a greased muffin tin.
Bake for 20–25 minutes, or until the cruffins are puffed and golden.
Step 3: Make the Filling
In a bowl, whisk together the Greek yogurt, powdered sugar, and vanilla extract until smooth.
Transfer the mixture into a piping bag or zip-top bag with a corner cut off.
Step 4: Fill and Finish
Once the cruffins have cooled slightly, use a knife or skewer to create a small hole in the center of each.
Pipe the Greek yogurt filling into the center of each cruffin.
Brush the outside of the cruffins with more melted butter and roll them in the remaining cinnamon-sugar mixture for that churro-like coating.