Preheat the oven to 400°F and spray a muffin pan with a non-stick spray with flour added, or line the muffin pan with liners.
Open up each of the four puff pastry sheets and lay them on the counter flat. Set two aside as they will be placed on top.
2 (17.3oz.) packages puff pastry
In a small bowl, whisk together the sugar and cinnamon. Set aside 4 tablespoons of the cinnamon-sugar mix to be used for sprinkling on after baking.
1 cup granulated sugar, 4 tablespoons ground cinnamon, ½ cup salted butter
Using a butter knife or offset spatula, spread ¼ cup of butter onto each of the bottom two sheets. Then generously sprinkles the large portion of cinnamon-sugar mixture on top of the buttered pastry sheets, covering the whole surface.
Place the remaining two pastry sheets on top of the cinnamon-sugar sheets.
Use a pizza cutter or pastry wheel to cut 6 equal strips from each pastry sheet stack.
Roll the slices up (cinnamon roll style), make sure to pinch the ends to help the rolls stay closed as they bake, and place each one into a muffin cup.
Bake for about 15 to 18 minutes or until golden.
Roll them around in the remaining 4 tablespoons of cinnamon-sugar mix that was set aside earlier while they are warm. Then serve immediately for best texture and flavor.