Start by peeling your sweet potatoes using a vegetable peeler.
Bring about 3.5 quarts (14 cups) of water to a boil in a large pot over high heat. Grab your peeled sweet potatoes and place them in the boiling water. They should be completely submerged in water, so if they are not, you may need to add a little more water. Let them boil until cooked through and fork tender (about 35-40 minutes or so).
About half way through (20 minutes in), make sure your rack is in the middle position and pre-heat your oven to 350 F.
Once your sweet potatoes are cooked through, drain the water. Let it cool for several minutes, or use a utensil to gently remove the potatoes from the pot. Place on a cutting board and slice into ½ inch slices.
In a small sauce pan on medium-low heat, add in your coconut oil until melted. Then add in your sugar, vanilla, cinnamon and non-dairy milk, stirring occasionally, until the mixture begins to slightly boil and thicken. Once it begins to boil, add in your pecans, stirring until they are evenly coated. Lower the heat, let it simmer for an additional 2-3 minutes. Then remove from heat.
Evenly place your sweet potato slices in an 8x8 pan (you should get about 2 layers). Then, pour your coconut sugar syrup mixture on top, evenly distributing it on the sweet potatoes. Optional: Add your marshmallows on top (you can add as many as you want but be mindful that they do expand!).
Place your pan in the oven and bake for 15 minutes. When the marshmallows are slightly browned, remove them from the oven and let them cool slightly before serving!
Hint: Keep in mind, the marshmallows will continue to brown after you have removed them from the oven. If you like yours extra crispy you can broil them for a minute or so like I did!