Roasted Beet and Butternut Squash Soup

1 butternut squash (or sweet potato), peeled, seeded and diced

canola or olive oil, for cooking

2-3 beets, trimmed

1 onion, chopped

2 garlic cloves, crushed

1 cup orange juice

1 L chicken or vegetable stock

1/4 cup half & half (optional)

sour cream, for serving (optional)