Prepare homemade pie crust according to recipe instructions. As per instructions, prepare, chill, roll out, and arrange into a 9 1/2" pie plate (do not bake). Return to refrigerator to chill while you prepare buttermilk pie filling.
Preheat oven to 400F.
Crack eggs into a large bowl and whisk until pale yellow and foamy (about 15 seconds).
Add sugar and stir until combined.
Add remaining ingredients and stir until mixture is smooth (I like to use a whisk to make sure I break up any flour clump).
Pour ingredients into prepared pie crust* and transfer to 400F (205C) and bake for 10 minutes. Then, without opening the oven door, reduce the heat to 350F (175C) and continue to bake another 40-45 minutes or until pie is set (the center may still be a bit jiggly but should not be liquidy. The top of the pie will be golden brown and may have puffed some, this will settle as it cools.
Allow to cool completely before serving.
*If you opted to use a storebought pie crust that's already in a foil tin, there's a good chance you'll have too much filling. Don't overfill your pie crust, discard any extra liquid.