Place the sweet potatoes in a large pot of water, filling the water a couple of inches over the tops of the potatoes. Add 2 tablespoons of kosher salt to the water and bring to a boil. Reduce heat and simmer for 15 minutes or until very tender. Drain; cool slightly.
Place potatoes in a large bowl and mash with a potato masher until you get a smooth consistency.
Add the butter, vanilla, bourbon, brown sugar, cinnamon, ¼ teaspoon salt and 2/3 cup of the chopped pecans to the bowl and stir to combine with the potatoes.
Pour the sweet potatoes into a buttered, 9″ x 13″ (2 quart) casserole dish and top with the marshmallows and the remaining 1/3 cup of pecans.
Bake for 25 minutes or until golden. If the marshmallows are getting too brown on top and the casserole isn’t warm yet, spray a piece of aluminum foil with cooking spray and cover the casserole dish until warmed through.