Preheat your oven to 350°F (175°C). Line a baking sheet or dish with aluminum foil for easier cleanup, if desired.
Wash the pumpkin and pat it dry. Using a sharp knife, carefully cut off the top portion of the pumpkin to create a lid. Set the lid aside. Scoop out the seeds and stringy pulp from the pumpkin using a spoon, creating a hollow cavity for the mince filling. Reserve the pumpkin seeds for roasting, if desired.
In a mixing bowl, combine the minced meat, chopped onion, minced garlic, breadcrumbs, grated Parmesan cheese, chopped parsley, dried thyme, dried rosemary, salt, and black pepper. Mix well until all the ingredients are evenly incorporated.
Spoon the mince filling into the hollowed-out pumpkin, packing it tightly and filling it up to the top. Place the pumpkin lid back on top.
Place the stuffed pumpkin on the prepared baking sheet or dish. Drizzle the exterior of the pumpkin with a little olive oil to help it brown and maintain moisture. Cover the pumpkin loosely with aluminum foil, leaving a small vent for steam to escape.
Transfer the baking sheet or dish to the preheated oven and bake for 1 hour 30 minutes to 2 hours, or until the pumpkin is tender when pierced with a fork and the mince filling is fully cooked. Remove the foil during the last 15-20 minutes of baking to allow the top of the pumpkin to brown slightly.
Transfer the baking sheet or dish to the preheated oven and bake for 1 hour 30 minutes to 2 hours, or until the pumpkin is tender when pierced with a fork and the mince filling is fully cooked. Remove the foil during the last 15-20 minutes of baking to allow the top of the pumpkin to brown slightly.