Preheat broiler to high and place an oven rack about 5 inches from heat source. Line a baking sheet with foil and mist with nonstick cooking spray. Stack 8 tortillas on a cutting board and use a sharp paring knife to trim away some of top, leaving a 1-inch "stem" so tortillas are shaped like pumpkins. Repeat with remaining 8 tortillas. Use a knife to cut two triangles for eyes and a crescent for a mouth into 8 tortillas.
Warm 1 teaspoon oil in a large skillet over medium heat. Add a tortilla without eyes and mouth, sprinkle with a scant 1/2 cup cheese. Cover with cutout tortilla. Cook until underside is golden, 1 to 2 minutes, slide onto baking sheet, and repeat to make three more quesadillas.
Place baking sheet under broiler and broil until tops are golden. Slide onto a serving platter and loosely tent with foil to keep warm. Repeat with remaining tortillas and cheese. Serve immediately.