1. Wash and peel your potatoes. I’ve heard a lot of people just peel their potatoes without washing them because… if you’re going to peel the skin off, why wash them? Well let’s see… potatoes grow in the DIRT and they are DIRTY. Seems like common sense, but if you don’t wash them BEFORE peeling them, you’ll get little specs of dirt on your peeled potatoes. Wash your potatoes people.
2. Slice potatoes into discs, roughly half a centimeter thick. For all my non-metric friends out there, think 2-3 silver dollars stacked on top of each other.
3. Line the bottom of your slow cooker pot with the first layer of potato slices, add salt and pepper to your taste or dietary liking, then add the next layer of potato slices and add salt and pepper again. Repeat this process until you’re out of potato slices or you get tired of doing it, whichever comes first.
4. Melt butter in a pot set on medium heat. As soon as the butter is melted, whisk in flour until the mixture becomes thick and doughy. Add sliced onions and minced garlic. Keep on whisking and gradually add the milk.
5. Add the shredded cheese and continue whisking until you have something thick, but smooth, or get tired of whisking, whichever comes first. Let’s be real, having pockets of semi-melted cheese in your dish can be a treat.
6. Pour your cheese sauce into the slow cooker pot on top of the layered potatoes. You may need to tip the pot back and forth so the sauce gets everywhere.
7. Cook on “high” in the slow cooker for ~3 hours, and then check every 15-30 minutes until you can easily poke through the potatoes with a fork (in the future, just remember how much time it took your slow cooker to get it perfect and you won’t need to do this again.) Use chives for garnish.
One of the big complaints of preparing potatoes au gratin in a slow cooker is that it’s hard to get a particularly crispy top layer, and that is the primary benefit of preparing this dish with an oven instead of a slow cooker. Honestly, though, I don’t find having a crisp top layer necessary to having a tasty potatoes au gratin dish.
It’s much more important to not overcook the potatoes beneath the top layer so that your potatoes au gratin don’t come out too mushy. With that in mind, depending on your slow cooker, your potatoes might be done before 3 hours is up, so if you’ve always found your cooker to cook things faster, adjust the cook time accordingly.