Preheat oven to 400 degrees F. Wash potatoes and poke each with a knife a few times to allow steam to escape. Place a piece of foil in the oven and then the potatoes on top (this is to catch any drippings). Cook for 40-50 minutes until fork tender. Allow potatoes to cool until you are able to handle them and peel off the skin (it comes off really easily).
Place peeled cooked potatoes in a large bowl with the butter, sugar, milk, eggs, and vanilla and beat with an electric mixer until mashed and combined well. Place potatoes in a 9x9 inch casserole dish or a deep dish pie pan.
In a small mixing bowl, combine all the topping ingredients until crumbly and then sprinkle on top. Refrigerate until ready to bake. Bake at 350 degrees F for 20-30 minutes until top browns.