1 winter squash (about 2 pounds), such as butternut or turban, unpeeled, seeded, and cut into 3-inch pieces
Extra-virgin olive oil, for drizzling
Coarse salt and freshly ground pepper, to taste
2 heads garlic, tops cut off to expose cloves
1 1/4 sticks (10 tablespoons) unsalted butter, room temperature
8 scallions, white and pale-green parts only, sliced 1 inch thick
2 chipotle chiles (canned in adobo sauce)
2 cups (16 ounces) sour cream
8 ounces cream cheese, room temperature
1 1/4 cups grated Parmesan cheese (about 4 ounces)
4 teaspoons fresh lemon juice
Paprika, for sprinkling
Roasted pepitas (pumpkin seeds), for garnish
Breadsticks, for dipping