What is your go-to cookbook?

Depends. I don't normally pull out specific recipes unless it's a special occasion or holiday. For holidays I like looking at old recipes that were provided by Old Sturbridge Village because we take a more rustic approach to food, the ingredients and even how to cook it. This week I made mulled cider per a 19th-century recipe, and in addition to the specified spices I also mulled it using an actual mulling iron (quite a task trying to heat it up to the right temperature especially when we don't have a fireplace).

My cookbooks are usually the backsides of microwave meals.

The Joy of Cooking. It is great and you can modify to your own taste.