Step 1

Gently stir the blackberries, white sugar, melted butter, lemon juice, and cornstarch in a large bowl until the sugar evenly coats the berries. Pour into the prepared baking pan. Wash and thoroughly dry the bowl.

Step 2

Add the flour, cornmeal, sugar, and salt to the clean bowl; stir well. Cut in the butter with a pastry cutter or a fork until the mixture resembles dry, coarse cornmeal. Stir in ¼ cup cold water, then more water in 1-teaspoon increments until the mixture becomes a soft but firm, supple, not-sticky dough.

Step 3

Gather the dough into a ball, dust it with flour, and roll it into a shape similar to the top of the au gratin dish (or the baking dish), following the instructions that begin on page It can be rustic and a bit malformed; it shouldn’t come up over the sides of the baking dish. Set it over the fruit. Brush it with the foamy egg whites and sprinkle evenly with the brown sugar.

Step 4

Bake the pandowdy for 30 minutes. Using the handle of a flatware knife, break the crust into irregular chunks and shards, maybe 7 or 8 large pieces. Continue baking until the filling bubbles up through the crust’s cracks and coats its ragged edges, about 20 minutes more. Cool the pan- dowdy on a wire rack for at least 25 minutes or to room temperature before scooping into bowls to serve. Store tightly covered in the refrigerator for up to 2 days.

Step 5

Pro Tip: The less you can work the crust, the more tender it will be. Gather the dough into a ball without making it too compact, dust it with flour as lightly as possible, and roll it in gentle but even strokes.

Step 6

Mix the cream and buttermilk in a large saucepan, then set it over medium heat and warm until small bubbles fizz around the inside perimeter of the pan. Meanwhile, use an electric mixer at medium speed to beat the sugar and egg yolks in a large bowl until pale yellow but very thick, until wide ribbons slide off the turned-off beaters, about 5 minutes.

Step 7

Beat about half the hot cream mixture into the egg yolk mixture in a slow steady stream until smooth, then beat this combined mixture into the remaining cream mixture in the pan until smooth. Beat in the vanilla extract and salt. Set the pan over low heat and cook, stirring constantly, until the custard thickly coats the back of a wooden spoon and the temperature registers 170°F, 4 to 7 minutes.

Step 8

Strain the mixture through a fine-mesh sieve into a clean bowl. Refrigerate for at least 4 hours or up to 2 days, covering once the custard is cold.

Step 9

To Freeze It: Prepare an ice-cream machine. Stir the cold custard and freeze it in the machine according to the manufacturer’s instructions, until you can scoop up a mound with edges that do not immediately melt. Store in a sealed container in the freezer for up to 2 months.

Step 10

A La Mode It: Set the frozen custard slightly to the side of any crust so that it melts into the blackberries but doesn’t soften said crust.

Step 11

Pro Tip: For a kick, add up to 1/8 teaspoon cayenne with the salt.