Preheat the oven to 190 degrees Celsius. Place the pumpkin halves, cut-side up, on a baking tray. Brush the cut sides with oil. Pop in the oven and roast for an hour and a quarter or until just tender. Set aside to cool.
Prepare the rice for the stuffing while the pumpkin is roasting. Cook in a saucepan of boiling water for 30 minutes or until tender then drain well.
To toast the walnuts for the stuffing, arrange on a baking tray and roast for 3 to 5 minutes. Cool then chop.
To finish the stuffing, heat oil in a large frying pan over medium heat. Cook onion, stirring, for 4 minutes until it softens. Add garlic and cook for 30 seconds or until aromatic then stir in rosemary and cinnamon.
Put the rice and onion mixture in a large bowl. Add lentils, fetta, baby spinach and toasted walnuts. Season the stuffing with salt and pepper. Stir to combine.
Use a spoon to remove the pumpkin seeds and membrane and discard. Scoop out the flesh leaving a 2cm thick shell.
To stuff the pumpkin, divide stuffing among pumpkin shells and press down firmly. Carefully place the pumpkin shells together and tie with kitchen string to secure.
Place on a baking tray and roast for 45 minutes or until heated through. Cut into slices and serve with tomato chutney. This rice and fetta stuffed pumpkin makes a delicious vegetarian roast.