Preheat the oven to 375 degrees.
Lightly grease 8 well os a muffin tin. Set aside.
Using a small rolling pin, roll out each sheet of puff pastry until you have 2 larger rectangles that are approx 11x15 inches.
Spread the softened butter onto the sheets.
Combine the sugar and cinnamon in a small bowl and whisk with a fork to combine.
Sprinkle a small amount of the cinnamon/sugar mixture on top of the buttered sheets.
Starting on the long end of the rectangle, roll up the dough tightly into a log.
Cut the dough in half, giving you shorter logs.
Then cut each of those logs in half, lengthwise - exposing the inner layers of the logs.
Repeat with the second sheet. When you are finished - you should have 4 pieces out of each sheet.
Take each piece and wrap it around your fingers to form the shape of a muffin, with the layered side out. This will give the best chance of all those layers being visible when they are baked.
Place each rolled piece in the greased muffin tin.
Bake for 30-35 minutes - rotating halfway through. Since all ovens bake a little different, check these in the last 10 minutes or so. For the puff pastry, you want them deep brown and crispy, but they can easily go too far and burn if they aren't watched because the sugar melts and puddles in the bottom of the pan. Left too long, the sugar will start to burn.
Remove from the oven and immediately remove from the pan, one by one, by gently releasing any parts that are stuck using a butter knife or thin object.
Roll each cruffin in the remaining cinnamon/sugar mixture and place them on a plate or cooling rack to come to room temperature.
Store at room temperature in an open container. Closing them into an airtight container will make them sweat and the sugar will become moist and they will lose the texture that makes them great.