Cover sweet potatoes with water and boil until tender. They are ready when a fork pierces the potato easily. Should take 20-30 minutes depending on size. Pour off hot water. Rinse with cold water until potatoes cool.
Peal off potato skin with a fork. Discard the.
Mix cooked sweet potatoes, cinnamon, vanilla, sugar, salt, milk and butter until combined. Taste the mixture and add more of each ingredient until it is to your liking. The mixture should be thick.
Unroll pie crust. Add half of the mixture on half of the crust. Leave space on the edges for crimping. Fold the other half of the crust over and crimp the edges. Cut a couple of small slits in the crust. Repeat with the second crust. The final product should look like a calzone.
Optional: These jacks can also be shaped into individual pastries. Use a large circular or square cookie cuter to make smaller jacks.
Bake the jacks on a cookie sheet for about 30 minutes or until crust is golden brown.
Let the jacks cool. Cut each jack into 4-6 slices. Serve alone or with a scoop of ice cream.