Preheat oven to 400F and lightly oil a casserole dish.
Cover a baking sheet with a piece of foil or parchment paper then wash and poke holes in the sweet potatoes with a fork.
Place the sweet pototatoes on the baking sheet and roast in the oven until very soft, about 45-60 minutes.
Once the poatoes have cooled a little, split them and scoop out the flesh.
Mash the sweet potato. My preferred way to do this is with a ricer because it makes them extra smooth.
In a large bowl mix together the sweet potato, butter, maple syrup, pumpkin pie spice, greek yogurt, and salt.
In the bowl of a mixer, whip egg whites to soft peaks.
Gently fold egg whites into mashed sweet potatoes and transfer to casserole dish.
Topping
In a bowl, mash together brown sugar and butter, then cut in oats, pumpkin pie spice and pecans.
Place topping on the sweet potatoes and then sprinkle with marshmallows.
Bake 30-40 minutes, until hot. If the topping starts to burn, cover with foil.
Notes
We’ve used fresh sweet potatoes in this recipe. We bake them and then use an Oxo Ricer to make them super smooth before adding them to our filling.
To make your holiday dinner easier, steps 1-6 of the filling can be done 1-2 days in advance. Bring the mixture to room temperature and whip it up before adding the beaten egg whites.
The pecan stuesel can be prepped too. Make it as written, then place in an airtight container and refrigerate.
This recipe is gluten-free, but always check your ingredients if one of your guests is gluten intolerant.
For a vegetarian version make sure to use vegetarian marshmallows.