Many variations of candied sweet potato casserole with marshmallows and pecans are popular around the holidays. It's a perfect sweet side dish and will even attract kids (and adults) who don't normally want to eat their vegetables. Experiment with your own flavor additions, such as candied ginger, maple syrup or a bit of cayenne pepper, to customize this dish into your own special holiday tradition.
Peel the sweet potatoes and cut into quarters. (Cut larger potatoes into sixths or eighths; all the pieces should be roughly the same size to ensure an even cooking time.) Rinse the potatoes in a colander, place them in a large pot and cover with water.
Bring the potatoes to a boil on high heat, then lower the heat and let them simmer until tender (when you can press a fork into the flesh with no resistance). Drain in the colander and transfer back to the pot or to the bowl of an electric mixer.
While the potatoes are cooking, toast the pecans in a frying pan over medium-high heat, moving them constantly so they don't burn, until they are lightly browned and smell toasty.
Mash the sweet potatoes by hand or mix them with an electric mixer until smooth. Add the spices, vanilla, sugar, orange zest, pecans, bourbon (if desired) and milk. Beat the eggs in a separate bowl, then stir into the potato mixture once it is cooled enough to not cook the eggs.
Transfer the potato mixture to a buttered or sprayed casserole dish and bake at 350 degrees for 20 minutes.
Top the casserole with mini marshmallows and return to the oven for about ten minutes or until the marshmallows are melted and lightly browned.