First, I recommend double checking the store. While I'm deeply annoyed by it, most grocery stores that I visit have more than one cheese aisle. Make sure you didn't accidentally miss it. Here in Nashville, you can find it at any Kroger, Publix, TJ's or Aldi. While ricotta isn't the specialty food it once was, I recognize that not everyone has access to a fully stocked grocery store. If this is the case for you, you have a few substitution options: 1. Make your own ricotta (don't worry, it's way easier than it sounds) 2. Use full-fat small curd cottage cheese (or blend large curd cottage cheese with an immersion blender until the consistency is right) 3. Use softened cream cheese thinned out with a bit of milk