Heat oven to 350 degrees
Place sweet potatoes in the oven and bake until tender, about 45-50 minutes
Whie the sweet potatoes are baking make the pie crust
Grind Biscoff cookies into fine crumbs
Mix with 6 tablespoons of softened butter
Press the mixture into a deep dish pie plate and bake for 10 minutes
Let cool to room temperature
When the sweet potatoes are tender remove them from the oven and let cool for about 15 minutes
Slice the sweet potatoes and place them into a food processor
add the melted butter, dulce de leche, vanilla and salt. Process until smooth
add eggs into the food processor and process until smooth
Pour the sweet potato pie filling into the prepared crust and bake in the center of the oven for 35-40 minutes until the filling has set
let the pie cool before slicicing
I drizzled a little dulce de leche over the top for garnish but that's optional