For the filling:

• 2 cups mashed sweet potatoes (cooked and peeled)
• 1 cup plain kefir
• 3/4 cup brown sugar (or coconut sugar)
• 2 large eggs
• 1 teaspoon vanilla extract
• 1 teaspoon cinnamon
• 1/2 teaspoon nutmeg
• 1/4 teaspoon ginger (optional)
• 1/4 teaspoon salt
• 2 tablespoons melted butter or coconut oil

For the crust:

• 1 1/2 cups graham cracker crumbs or crushed digestive biscuits
• 1/4 cup sugar
• 6 tablespoons melted butter

Instructions summary:

1. Preheat the oven to 350°F (175°C).
2. If making a crust, mix the crumbs, sugar, and butter, press into a pie dish, and pre-bake for 8-10 minutes.
3. Blend sweet potatoes, kefir, sugar, eggs, vanilla, spices, salt, and melted butter until smooth.
4. Pour the filling into the crust.
5. Bake for 45-50 minutes until the center is set.
6. Let cool completely before serving.