Preheat the oven to 375°F (190°C). Spray a 12-cup muffin pan with cooking spray and set aside.
Unroll the crescent dough and press seam lines together to form one sheet. Roll or press the dough into an approximately 8×18-inch rectangle.
Cut the dough into 12 equal squares and press each square into a muffin cup so the dough forms a small cup.
Divide the mozzarella evenly and place about 1 tablespoon of shredded mozzarella into the bottom of each dough cup.
Place one piece of frozen popcorn chicken in each cup (use two smaller pieces if needed to fill the cup).
Spoon about 2 tablespoons of spaghetti sauce over each piece of chicken, dividing the 1 1/4 cups among the 12 cups.
Sprinkle shredded Parmesan evenly over the top of each cup.
Bake in the preheated oven for 15 to 18 minutes, or until the crescent dough is golden brown and the chicken is heated through.
Remove from oven and let cool in the pan a few minutes before transferring to a wire rack to finish cooling slightly, then serve.