preheat oven to 350

mix butter and pretzels together and mash into bottom of a 9x13 pan bake for 13 mins.

mix sweet potatoes, egg, cornstarch, vanilla and spread on top of the pretzels and bake again for 15 mins.

remove from oven and let cool completely. while cooling mix cream cheese, cool whip and 1 cup sugar into a large bowl and beat until mixed well.

after sweet potatoes have cooled add cool whip mixture on top and garnish with broken pretzel pieces.

place and store in fridge best if made night before serve cold