Preheat oven to 350ºF and make sure the rack is in the bottom third of the oven. You want the heat from the bottom of the oven to cook the bottom crust of the pie; so the lower you set your rack the better the crust will bake.
Prepare a single-crust 9" pie crust. (Or use store bought.) With a fork poke some holes in the crust once it's in the pan and the edges are crimped.
In a small bowl whisk together the sugar, flour and nutmeg. Set aside.
In a medium bowl, beat the 2 eggs until well broken up and mixed together.
Whisk in the buttermilk, melted butter and vanilla.
Stir the sugar mix into the buttermilk mixture.
When this is well combined, pour into the prepared pie crust.
Bake for 35 to 45 minutes until golden brown and the middle just jiggles a little.
It's best served completely cooled, but can be served slightly warm.