Gentl & Hyers
The sweet maple syrup imparts a subtle, but not overwhelming flavor to the buttermilk custard, and the star of the pie is the cornmeal crust, which is a welcomed change from traditional pastry crusts in this pie from the Four and Twenty Blackbirds cookbook.
Stir the flour, cornmeal, salt, and sugar together in a large bowl.
Add the butter pieces and coat with the flour mixture using a spatula.
With a pastry blender, cut the butter into the flour mixture, working quickly until mostly pea-size pieces of butter remain (a few larger pieces are okay; be careful not to over blend).
Combine the water, cider vinegar, and ice in a large measuring cup or small bowl.
Sprinkle 2 tablespoons of the ice water mixture over the flour mixture and mix and cut it in with a bench scraper or spatula until it is fully incorporated.
Add more of the ice water mixture, 1 to 2 tablespoons at a time, and mix until the dough comes together in a ball, with some dry bits remaining.
Squeeze and pinch with your fingertips to bring all the dough together, sprinkling dry bits with more small drops of the ice water mixture, if necessary, to combine. Shape the dough into a flat disc, wrap in plastic, and refrigerate for at least 1 hour, preferably overnight, to give the crust time to mellow. If making the double-crust version, divide the dough in half before shaping each portion into flat discs.
Wrapped tightly, the dough can be refrigerated for 3 days or frozen for 1 month.
Position a rack in the center of the oven and preheat the oven to 325 degrees F.
Place the prebaked pie shell on a rimmed baking sheet.
In a large bowl, mix together the flour, cornmeal, brown sugar, salt, and melted butter.
Add the vanilla paste (or vanilla extract) and the sour cream and stir until smooth.
Add the eggs and egg yolk one at a time, blending well after each addition.
Add the maple syrup and buttermilk and mix until smooth.
Strain the filling through a fine-mesh sieve directly into the pie shell, or strain it into a separate bowl and then pour it into the shell.
Bake on the middle rack of the oven for 45 to 55 minutes, rotating 180 degrees when the edges start to set, 30 to 35 minutes through baking.
The pie is finished when the edges are set and puffed slightly and the center is no longer liquid but still quite wobbly.
Be careful not to overbake or the custard can separate; the filling will continue to cook and set after the pie is removed from the oven.
Allow to cool completely on a wire rack, 2 to 3 hours.
Serve slightly warm, at room temperature, or cool.
The pie will keep refrigerated for 2 days or at room temperature for 1 day.