Preheat oven to 350. Prepare pie pan with pie crust.
Once fully combined and slightly fluffy, add flour and eggs.
Mix well. You can use a hand mixer for this, or beat with a fork until fully combined and smooth.
Stir in buttermilk and vanilla extract. Mix until fully incorporated.
Bake for 1 hour and 15 minutes at 350 – or until done. A fork or toothpick inserted into the middle should come out cleanly. The pie will still be slightly jiggly after baking.
Allow time to cool and set before serving, usually an hour at the very least.