Buttermilk Basil Salad Dressing

1 cup buttermilk
1 cup sour cream
1/4 cup plus 2 teaspoons grated Parmesan cheese
3 tablespoons minced fresh basil
1 teaspoon onion salt
2 garlic cloves, minced
Torn mixed salad greens

In a bowl, combine buttermilk and sour cream. Stir in Parmesan cheese, basil, onion salt and garlic. Cover and refrigerate for at least 1 hour. Serve over salad greens. Makes 2 cups.