Preheat oven to 350 degrees if baking now.Grease a 2-2.5 qt ovenproof serving dish with half of the filling ingredients butter. I use Corningware Casserole dishes.Mix the filling ingredients in a bowl. Fill the greased ovenproof dish with the filling.Melt the remaining butter on med-low in a pan and add the chopped pecans, lightly toasting them. Mix the remaining topping ingredients, except the marshmallows, and stir into the toasted pecans until well-mixed.Spread the topping marshmallows evenly across the top and sprinkle the nut mixture over the entire dish.When the oven is ready, place the casserole dish uncovered in the oven for 30 minutes until the top has browned.Remove and serve.
If making Ahead of Time
Cover and refrigerate for 1-4 days until ready to cook.