Start by peeling and chopping your sweet potatoes. Place in a pot of boiling water and cook until tender (can easily pierce with a fork).
Remove from heat and strain the water from the potatoes in a colander.
Place your potatoes, milk, vanilla extract and cinnamon in a bowl or Kitchen Aid and mix until pureed.
Transfer the sweet potato puree into a prepared baking dish and put to the side.
In a separate bowl, mix together the pecans, brown sugar, flour and a dash of salt.
Add in the melted butter to the nut and sugar mixture and combine. This will be the topping.
Spread the nut topping over the top of the sweet potato puree. Cover with aluminum foil and bake on 350 for 20-25 minutes.
Optional - before serving, add some marshmallows. I make a few strips on top with the marshmallows so that those who want to have without can enjoy.
Bake in the oven before serving uncovered until the tops of the marshmallows and pecans are golden brown.