When asked to bring a green vegetable to a holiday meal, why not really get into the spirit of things and smother that green vegetable in butter, cream, and two kinds of cheeses?
Enter stage right: Creamed Spinach Gratin via the Barefoot Contessa, Ina Garten. Generally, I find that Barefoot Contessa recipes are tried and true, relatively simple to make, and absolutely bursting at the seams with high-fat dairy products. The woman likes her butter, if you know what I mean. While not always ideal for every day, her recipes are perfect for holidays or parties where you just want a dependable crowd-pleaser, cholesterol levels be damned.
Bonus: this can be fully assembled up to two days ahead and baked half and hour before you eat. Easy. Also, I substituted Edam for Gouda because the Edam was in the markdown cheese basket, beckoning to my little cheapskate heart.