Preheat oven to 400°F.
On a medium-floured surface, unfold the puff pastry sheet so that it lays flat. Use fingers to pinch the two sides of the creases together to reinforce the dough.
Using a rolling pin, stretch the puff pastry by about 1/4 inch on all sides so make it slightly thinner.
Spread the leftover spinach artichoke dip evenly over the entire sheet, going very close to the edges.
Roll tightly from one short edge to create a smooth, even roll.
Using a sharp knife or a blade pizza cutter, cut 12 pinwheels, about 1/2" to 3/4" wide.
Place pinwheels flat on a parchment-covered baking sheet at least 1 inch apart as the pinwheels will puff up during baking. Reshape any as needed to make round again after cutting.
Sprinkle a little grated Parmesan on top of each.
Bake for 18-20 minutes or until the puff pastry and the Parmesan topping are golden brown.
Serve warm or cold.