Except for one dream-worthy buttermilk pie that I had at Husk in Nashville, which was made by the uber-talented pastry chef Lisa Donovan, I have no connection to this Southern specialty. But I couldn’t get that pie out of my head, and I couldn’t stop thinking it would make a good bar cookie. It does. Both the custard top and the cornmeal crust are soft, but each holds a surprise: The crust has a bit of sandiness and the topping, all silk-and-velour, has the pop of beautiful berries. As for tastes, you get sweet, salty and wholesome grain flavors from the crust and a soothing mix of warmth and tang from the custard.
The pie bars are good at room temperature or chilled, served unaccompanied or brought to the table with lightly sugared blueberries, mixed berries or blueberry syrup. They certainly don’t need it, but they’re nice with whipped cream.
Excerpted from Dorie’s Cookies.
Blueberry-Buttermilk Pie Bars
Adapted from Dorie’s Cookies
Makes 16 squares
FOR THE CRUST
3/4 cup (102 grams) all-purpose flour
1/3 cup (67 grams) sugar
1/4 cup (33 grams) cornmeal (not coarse)
2 tablespoons cornstarch
1/4 teaspoon fine sea salt
1 stick (8 tablespoons; 4 ounces; 113 grams) cold unsalted butter, cut into 8 pieces
FOR THE TOPPING
1 1/2 tablespoons cornstarch
1 1/2 cups (360 ml) buttermilk
4 large eggs, at room temperature
1/2 cup (100 grams) sugar
Pinch of fine sea salt
2 teaspoons pure vanilla extract
2 tablespoons (1 ounce; 30 grams) unsalted butter, melted and cooled
1 cup (150 grams) fresh blueberries
TO MAKE THE CRUST: Have an 8-inch square baking pan at hand.
Put the flour, sugar, cornmeal, cornstarch and salt in a food processor and pulse a few times to blend. Drop in the chunks of butter and work in long pulses — about dozen or so — until you have a moist dough that forms curds. Turn the dough out into the baking pan and use your fingertips to press it evenly into the pan. Put the pan in the refrigerator while you preheat the oven (it needs a short chill before baking).
Center a rack in the oven and preheat it to 350 degrees F.
Bake the crust for 23 to 25 minutes, until it’s golden brown. Even though the crust will be baked again with the topping, it needs to be thoroughly baked now, so err on the side of more golden rather than less. Transfer the pan to a rack and allow the crust to cool completely.
If you’ve turned off the oven, return it to 350 degrees F.
TO MAKE THE TOPPING: Spoon the cornstarch into a small bowl and pour over 1/4 cup of the buttermilk. Stir until the cornstarch dissolves; this is a slurry, which will thicken the custard.
Whisk the eggs in a medium bowl until foamy. Add the sugar and immediately start whisking vigorously (you must beat sugar and eggs together quickly, or the sugar will “burn” the yolks and cause a film to form). Whisk in the salt and vanilla, then whisk in the slurry. When the slurry is fully incorporated, stir in the remainder of the buttermilk, followed by the melted butter. Scatter the blueberries over the crust and then pour on the topping. The blueberries will shift — they’ve got nothing to hold on to — so try to even them out by poking them with your fingers or a spoon; but give up if it’s not happening.
Bake the bars for 42 to 45 minutes, until the topping is puffed all the way to the center, brown around the edges and firm everywhere. Transfer the pan to a rack and cool for 20 minutes. Carefully run a table knife around the edges of the pan, place a piece of parchment paper over the pan and unmold the bar onto a rack. Remove the pan and invert the bar onto another rack to cool to room temperature; chill if you’d like. Just before serving, slide the bar onto a cutting board and, using a long, thin knife, cut 2-inch squares.
STORING: Covered and kept away from foods with strong odors, the bars will keep for a day or two in the refrigerator. However, like “real” pies, these are best the day they are made.