In a large saucepan melt butter over medium heat. Add onion and garlic; sauté onion until it is clear. Whisk in flour, salt and pepper until smooth. While whisking, gradually add milk and chicken broth. Add in potatoes, bacon, corn and parsley flakes.
Continue to heat over medium to low heat, stirring frequently until chowder has thickened, about 20 minutes. Remove from heat.
Whisk in grated cheese and sour cream, stir until cheese has melted.
