Preheat oven to 375 degrees.
Put sweet potatoes into a pot large enough for the potatoes to be covered in water. Add cold water until the potatoes have been submerged. Cover with a lid.
Bring potatoes to a boil, then simmer on medium heat for 20-25 minutes. Potatoes should be soft enough that a butter knife can be pierced through the thickest part of the potato.
While the potatoes are simmering, mix both sugars, nutmeg, cinnamon, and salt in a medium mixing bowl.
Take a third cup of the brown sugar mixture and put in a small bowl with the pecans. Set aside.
Pour the melted butter, vanilla, and bourbon into the bowl with the remaining brown sugar mixture. Mix together with a whisk. Set the sauce aside.
Once potatoes are cooked, remove from heat and run under cold water so they’re cooler to the touch, for about 5 minutes. Peel off the skin, and set the peeled potatoes to the side on a cutting board. Slice the potatoes about a quarter inch thick.
Into your casserole dish of choice, add the sweet potato slices. Evenly pour the brown sugar sauce over the potatoes.
Evenly sprinkle the pecan mixture over the potatoes.
Bake the potatoes, uncovered, for 15 minutes.
Can be served immediately.