Preheat oven to 400°CF/205°C.
Using a pumpkin carving or small sharp knife, cut lid off pumpkin and scoop out insides with a large spoon, leaving a large hollow. Set aside.
Add pecans to small skillet and toast on stovetop on low-ish heat for 10 minutes or until fragrant.
Place in blender/food processor and blend for 6-8 seconds, until pecans are small pieces. Set aside.
To large skillet, add 1 tablespoon of oil. When oil is hot add diced celery and onion, and sauté on medium-high heat for 5-6 minutes (until onion is translucent). Add garlic and sauté for 2 more minutes.
Add cooked rice, cranberries, pecans, sage, rosemary, onion powder, remaining oil, 3 tablespoon water, black pepper and salt to skillet. Cook for 8-10 minutes, stirring frequently. (Mixture should be crumbly.) Adjust seasoning if needed and remove from heat.
Brush inside and outside of pumpkin with olive oil, and season inside well with salt and pepper.
Spoon pumpkin filling into pumpkin - packing it fairly tightly - and place the top of the pumpkin back on.
Wrap pumpkin completely in a layer of aluminum foil and place on baking sheet. Bake in preheated oven for 45-50 minutes.
Remove foil and bake pumpkin, uncovered, for a further 10 minutes. (The pumpkin is ready when you can easily push the tip of a knife into the skin.)
Remove from oven and serve cut into four wedges with your favourite seasonal greens or salad, mashed potatoes and gravy (if desired). Optionally garnish with parsley.