Place all these ingredients in a sauce pan, bring to a boil and simmer for 30 min. or until sweet potatoes are tender.
Thicken: 3 Tablespoons cornstarch in ¼ cup water. Stir into apple mixture until thickened. Remove from heat.
Process pecans in food processor until fine, add flour, salt and brown sugar, and spices - pulse until mixed. Add chunks of butter and pulse until mixed well.
Place 2/3 of the crust mix into a pie dish and pat into flat crust. Add apple mixture, and sprinkle the remaining crust mix over the top.
Bake at 375°F for about 20 minutes.