Prepare the butternut squash. Cut the butternut squash in half. Rub the cut side with a little oil and brown sugar (see step-by-step pictures). Place the butternut squash on a baking sheet cut-side down.
Roast the butternut squash for 45 minutes. When it's done, a fork should slide right through. If it's not done, roast it for 5-15 more minutes depending on its size.
Let it cool down. Then, scoop out the flesh at the center, leaving about 1 inch (1,3cm) of flesh on the sides.
Make the chimichurri
Make the chimichurri. Wash the parsley and remove thick stems. Cut the chili in half and remove the seeds. Chop them finely with a knife or in a food processor. Combine with olive oil, red wine vinegar, garlic clove (leave it whole), oregano, and salt.
Make the rice filling
Chop the veggies for the stuffing. Peel the onion and the carrots. Wash the celery. Finely mince the onion, carrots and celery with a sharp knife or in a food processor.
Sauté the veggies. Heat a pan or skillet with olive oil. When hot, add in the vegetables and sauté for 5 minutes over high heat while stirring continuously.
Cook the rice. Reduce to medium heat. Add the rice and poultry seasoning to the pan with the veggies. Sauté for 2 minutes. Pour the vegetable broth on top, cover with a lid, and simmer for 20 minutes (or according to the cooking time of your rice).
Stir in the scooped-out butternut squash flesh, crushed walnuts, and cranberries. Give it a good mix. Adjust seasoning if necessary.
Fill the butternut squash boats with stuffing. They should be heaping full. Serve with chimichurri.
Notes
If you're serving it as a main dish, 1 stuffed butternut squash boat equals 1 serving.
If you're making it ahead of time, reheat the butternut squash boats for 10 to 12 minutes in a preheated oven at 350°F (180°C).