Every year my family's Thanksgiving spread absolutely needs to include a creamy, marshmallow-topped sweet potato casserole. It's essential. I've made a lot of variations of this iconic dish, and over the years I've learned that what makes it so great isn't the topping — it's the way you treat the potatoes. This is the easy, but important trick you need to know.
Bake the Potatoes Whole for a Sweeter Flavor
Before you get to the actual casserole assembly, you've got to cook your sweet potatoes until they're soft and tender all the way through. There are a couple different ways to get there. But when your goal is cooking up the most flavorful, sweetest sweet potato casserole, you want to start by baking the potatoes whole.
It's true that peeling, chopping, and boiling or steaming the potatoes is the fastest method. When you put in the extra time to bake the potatoes in the oven, though, your efforts are handsomely rewarded.
Why Baking Is Best
So what exactly makes baking so much better than boiling or steaming — especially since it takes about twice the time? It's as simple as this: Baking sweet potatoes whole concentrates their flavor and sweetness, resulting in a sweeter casserole without loads of extra added sugar.
Most recipes will instruct you to bake at an oven temperature of 350°F to 375°F, which takes about an hour for soft and tender potatoes. It's also a completely hands-off task and can be done up to several days in advance. Go ahead and pop the sweet potatoes in the oven and let them cook while you prep the turkey brine, make pie crust, or set the table.
Even if your go-to recipe calls for boiling, it's easy to start by baking the potatoes instead. You can expect the same result, with the exception that the potatoes will taste naturally sweeter.
And if you have the time, don't be afraid to take the oven temperature even lower. According to food scientist Harold McGee, sweet potatoes contain an enzyme that breaks down the vegetable's starch into sugar. The catch, however, is that the enzyme does its best work when the potato is between 135°F and 170°F.