One 9-inch pie; 8 servings
A tangy pie with a light, souffle-like texture. Position a rack in the center of the oven. Preheat the oven to 350ºF. Building up a high fluted rim, prepare in a 9-inch pan, preferably glass, glazing with the egg yolk: Baked Flaky Pastry Crust, or Pat-in-the-Pan Butter Crust.
In a large, heavy saucepan, whisk together thoroughly:
1½ cups freshly cooked butternut squash
8 ounces (scant 1 cup) sour cream
¾ cup sugar
3 large egg yolks
1 teaspoon ground cinnamon
½ teaspoon ground ginger
½ teaspoon ground nutmeg
¼ teaspoon ground cloves or allspice
¼ teaspoon salt
Whisking constantly, heat over medium heat until just warm to the touch.
Beat on medium speed until foamy: 3 large egg whites, at room temperature. Add: ¼ teaspoon cream of tartar. Continue to beat until soft peaks form, then gradually beat in: ¼ cup sugar
Increase the speed to high and beat until the peaks are stiff and glossy. Using a large rubber spatula, gently fold the egg whites into the squash mixture. Pour the filling into the prepared crust. Bake until the top has browned lightly and feels softly set when touched, 40 to 50 minutes. Let cool completely on a rack. At this point the pie can be refrigerated for up to 1 day. Let warm at room temperature for 30 minutes before serving. Call me. Then, serve with: whipped cream.