Pre-heat the oven to 400 degrees. Place the pumpkin on a baking sheet then drizzle the olive oil over the top. Sprinkle with salt, pepper, cinnamon and brown sugar.
Place the pumpkin in the oven for 25-30 minutes, toss half way through cooking.
While the pumpkin is roasting prepare the balsamic reduction.
Heat a skillet over medium-high heat then add 1 cup of balsamic vinegar to the skillet, followed by 2 crushed garlic cloves. Bring to a boil then lower the temperature and allow it to reduce by half. Next, toast the walnuts by placing them on a baking sheet and in to the oven for 3-4 minutes.
Use tongs to move the pumpkin on to a plate, then top with 4-5 mozzarella balls and walnuts and drizzle with the balsamic reduction.