Remove seeds and pulp from the pumpkin. Peel the skin and cut into bite-sized pieces. Place pumpkin and water in a microwave-safe container, cover loosely with plastic wrap, and microwave at 600W for 4 minutes. Let it sit for 1 minute to cook through with residual heat. Mash until smooth and mix in sugar and salt to create pumpkin paste.

Spread the pumpkin paste evenly over the pizza dough. Sprinkle pizza cheese on top. Bake in a toaster oven for 6-7 minutes until the cheese is golden and bubbly.