Set your oven to 350°F and place your unbaked pie crust into a 9-inch deep-dish pie plate today. Press the edges firmly to create a pretty fluted design that will look beautiful after the pie is baked.

In a medium bowl, whisk the granulated sugar and the all-purpose flour together until they are very well blended. Mixing the flour with the sugar first prevents any dry lumps from forming in your final smooth custard.

In a large mixing bowl, beat the three large eggs using an electric hand mixer on a medium speed. Continue beating for about two minutes until the eggs look very pale, frothy, and slightly thickened in the bowl.

Slowly add the sugar and flour mixture into the beaten eggs while continuing to mix at a low speed. Stir until the sugar is fully incorporated and the batter looks like a thick and very creamy yellow paste.

Pour the cooled melted butter into the egg mixture and stir gently with your rubber spatula or a whisk. Make sure the butter is not hot so it does not cook the eggs prematurely while you are mixing.

Slowly pour the one cup of buttermilk into the bowl and whisk until the entire mixture is very smooth. The buttermilk provides the signature tangy flavor and creates the velvety texture that makes this Southern pie very famous.

Mix in the fresh lemon juice, pure vanilla extract,salt and ground nutmeg into the liquid pie filling today. These small additions balance the heavy sweetness and give the custard a very complex and bright aroma — similar to the bright citrus tang you get from these zesty lemon bars with a buttery shortbread base.

Pour the buttermilk mixture carefully into your unbaked pie shell, making sure not to spill any over the edges. Fill it almost to the top so the custard has plenty of room to puff up while baking.

Place the pie in the oven and bake for fifty to sixty minutes until the top is golden brown. The center should have a very slight jiggle when moved but should feel set and firm to the touch.

Remove the pie from the oven and place it on a wire rack to cool for two hours. Cooling is a very important step because it allows the custard to set perfectly before you slice into it.