This recipe comes from the Vegetarian Times website. I have added roast garlic to the mix, just because I like garlic. I seldom remember to buy buttermilk so I just use plain milk, although sour cream would be closer.
4 large russet potatoes
1 small butternut squash, halved and seeded
4 garlic cloves, unpeeled
2 Tbs. unsalted butter
1 cup low-fat buttermilk
½ cup chopped chives
½ cup grated Parmesan cheese
salt & pepper to taste
Preheat oven to 350F. Drizzle a little olive oil over the cut squash halves and garlic cloves. Place potatoes and squash halves (cut side down) on baking sheet. Nestle the garlic under the scooped out section of the squash. Bake 1 hour, or until both squash and potatoes are tender.
Cut potatoes in half lengthwise, and scoop insides into large bowl, leaving thin layer of potato. Reserve potato skins. Scoop flesh from squash into same bowl. Squeeze garlic insides into bowl. Mash. Stir in butter, chives, buttermilk and cheese. Add salt and pepper.
Fill potato skins with mash, and place on baking sheet. Broil 10 minutes, or until tops begin to brown. Serve hot.
If making ahead, cover, refrigerate. Bake at 400F for about 20 minutes until warmed and tops brown.