Serves 6 (serving size: 2/3 cup)
Heat butter and olive oil in a large saucepan over medium heat. Add onion and sugar to pan; cook 5 minutes or until soft, stirring frequently. Add butternut squash, water, and chicken stock. Bring to a boil; reduce heat, cover, and simmer 20 minutes or until squash is tender. Remove from heat, and puree with an immersion blender until smooth. Stir in salt, pepper, and buttermilk. Divide among 4 serving bowls; top each with 1 1/2 teaspoons toasted pumpkinseeds.