I just made a Lobster/Shrimp Mac and Cheese. Though I was apprehensive I used the Parmesan the recipe asked for. I grated the Parmesan fresh and used a double boiler. The cheese was accompanied by gruyere, and sharp cheddar. I mixed all of the cheeses per the recipe and slowly added heavy cream as requested. Why is my Parmesan always gritty? This is awful and a waste of money. Thoughts?