In a large saucepan, melt butter over medium heat. Cook onions, covered for 5 minutes or until softened.
Remove lid and increase to medium high heat. Add celery, carrot and garlic, cook, stirring for 8 minutes or until becoming golden.
Add apples, sage and thyme to pot and cook, stirring for about 7 minutes or until apples are softened.
Add sweet potato and broth and bring to a boil. Reduce heat; cover and simmer for about 20 minutes or until sweet potatoes are very tender.
Place soup in blender, in batches and puree until smooth.
Return to saucepan and stir in cream to heat through. Season to taste with salt and pepper.
Serve in shallow bowls sprinkled with cheese.