How do you make Olive Garden Parmesan peppercorn sauce?

According to the Bulk Peppercorns website the recipe is:

3/4 cup Buttermilk

1/2 cup Mayonnaise

2 teaspoons Freshly ground black pepper

1 teaspoon Garlic powder

1 teaspoon Onion powder

1/2 teaspoon Cayenne pepper

Mix all ingredients well and cool before use.