This is the perfect time to pull out my recipe for squash and potato gratin. The weather is getting cooler, the leaves are changing, and there is frost in the air around here. It’s that time of year when I don’t mind turning on my oven, and in fact welcome the warmth, and when my interests turn to comfort food, like my Beer Braised Pulled Chicken Tacos. And this gratin.
I’ve been making this recipe for several years now, sometimes even making it at mid-summer now that I have my little Breville toaster oven, which doesn’t heat up the house as much, so I’ve tried different combinations of squash and potatoes and cheese. One secret that I’ve found is that you need a fairly equal balance of squash and potatoes. Too many potatoes, and what’s the point? You might as well make a potato gratin and be done with it. Too much squash and you are going to end up with a watery gratin since you don’t have enough potato starch to thicken it. As with many things in life, it’s all about balance.
Another secret is using yellow potatoes. Yellow potatoes are the best of both worlds in a gratin since they are waxy so they stay together while also having a creamy, soft texture that melts into the dish.
One thing I love about this squash and potato gratin is that, beyond being a filling and tasty vegetable side dish, it’s not at all fussy. You randomly grab handfuls of sliced squash and sliced potatoes until you have a nice layer and then scatter some cheese and herbs about. Drizzle it with a bit of cream. And then do it again to make another layer. I like three layers since I think it distributes the flavor of the cheese throughout the dish, but I have made it with two layers and all the cheese sandwiched in the middle. It works either way. I will say that the cheese is best inside the gratin, as opposed to being scattered on top, since it stays all soft and gooey when it’s on the inside.
The only somewhat fussy part of the recipe is peeling the potatoes. And peeling the potatoes is optional. If you’re not in the mood to peel, you are still going to have a yummy gratin. (Just make sure to wash those potatoes well!)
Even the timing isn’t fussy. I had the very bad luck of having our power go out right in the middle of making this dish. We sat in the dark for two hours while I fretted that I wouldn’t have enough light to take the pictures or that the gratin wouldn’t be any good by the time we got the power back. But all was well! Once the power came back, I warmed the gratin up and then added the parmesan topping and let it brown to the beautiful golden color you see above in my oval baking dish from Bennington Potters. I love this dish and use it all time since it’s both pretty and functional.
You can certainly cut the squash and potatoes by hand for this gratin. Or use a food processor. However, if you want fast and even slices, I would highly recommend a mandolin. I have two mandolins, but this GSD mandoline is the one I always use. It’s sturdy. It’s well made. It has put in years of good service in my kitchen. Also, and this one is very important, it’s easy to use. The different blades simply snap into place and then you are ready to go. My other mandolin is more adjustable and can do a wider range of thickness, but it takes me so long to remember how to put it together that I never bother. (It also makes me nervous for some reason. It just doesn’t seem friendly.)
- 2 small yellow squash, or 1 medium
- 3 medium yellow potatoes, such as yukon gold, peeled
- 1 tbsp olive oil
- ½ tsp kosher salt
- 4 oz goat cheese
- 1½ oz parmesan cheese, shredded
- 4 tbsp heavy cream
- 6 tbsp fresh basil leaves, thinly sliced
- Preheat oven to 400F. Grease a 9x13 (or equivalent) casserole dish.
- Slice the squash and potatoes to about 2 mm thick, using a knife, a food processor, or a mandolin.
- Once the squash and potatoes are sliced, put them in a large bowl and toss them with olive oil and salt.
- Layer one third of the squash and potatoes in the prepared casserole dish. Top with 2 oz of goat cheese, ½ oz of parmesan cheese, 2 tbsp of heavy cream, 2 tbsp of basil. Repeat to make the next layer. Top it off with the remaining ⅓ of squash and potatoes. (You will have ½ oz of parmesan cheese and 2 tbsp of basil remaining.)
- Cover the casserole dish with foil and put in the oven for 45 minutes.
- Take the foil off and top casserole with remaining ½ oz parmesan cheese and 2 tbsp of basil. Bake for an additional 15 minutes.
- Remove the casserole from the oven and let it sit for 15-20 minutes to allow the juices from the squash to be absorbed and for the casserole to solidify.
Also, I like to reserve a handful of potatoes for the very top covering layer. It's not necessary to the dish, but I think it's looks nice and, since the potatoes stick together in stacks when sliced on the mandolin, it's easy for me to leave one stack for the end.