To make the dough: In the bowl of a food processor fitted with the metal blade or in the bowl of an electric mixer fitted with the dough hook and set on low speed, combine the butter, flour, sugar, and lemon zest and pulse or mix until the mixture is coarse and resembles wet sand. Add the egg and egg yolk and blend until the mixture comes together and forms a ball. Wrap the dough in plastic and refrigerate for 1 to 2 hours, or until firm.

Preheat the oven to 375°F.

On a lightly floured surface, roll the dough into a large circle that is 12 to 14 inches in diameter. If the edges crack, patch and roll again. Transfer the dough to a baking sheet.

To make the filling: In a large mixing bowl, toss together the apples, pear, nectarine, raspberries, flour, 1 tablespoon of the sugar, and the cinnamon until lightly coated.

Pile the fruit in the center of the dough, leaving a 1½-inch border, then fold up the outer edges of the dough to form a rustic edge and partially cover the fruit. Brush the edge of the dough with the milk and sprinkle with the remaining teaspoon of sugar.

Bake for 35 to 40 minutes, or until the tart is golden brown and the fruit inside is tender. Serve warm or at room temperature.