Put oats, cornmeal, sugar, and salt into a food processor and pulse to make a gritty meal. Add flour and pulse to mix. Scatter butter over dry mixture and pulse five or six times, until butter is cut into pieces the size of split peas.

Sprinkle egg mixture over flour mixture in processor. Pulse just until mixture starts to form clumpy crumbs. Do not overprocess.

Transfer crumbs to a large bowl. Pack dough together, as you would a snowball, but don’t overdo it. Place dough on a piece of plastic wrap and flatten into a ¾-inch-thick disk. Wrap in plastic wrap and refrigerate for 1 to 1 ½ hours before rolling. The dough should be slightly pliable, not rock-hard, when you roll it.