Preheat oven to 350°.
To prepare crust, place crackers in a food processor; process until crumbly. Add 2 tablespoons sugar, butter, and 1 egg white; pulse 5 times or just until moist. Press crumb mixture evenly into a 9-inch pie plate coated with cooking spray. Bake at 350° for 8 minutes; cool on a wire rack for 15 minutes.
Reduce oven temperature to 325°.
To prepare filling, spoon yogurt onto several layers of heavy-duty paper towels; spread yogurt to 1/2-inch thickness. Cover with additional paper towels; let stand 5 minutes. Scrape into a bowl using a rubber spatula. Place cream cheeses and vanilla in a bowl; beat with mixer at medium speed until smooth. Add eggs, one at a time, beating well after each addition. Combine sugar, flour, and salt, stirring with a whisk. Add sugar mixture to cheese mixture; beat until combined. Add yogurt to cheese mixture; add eggnog. Beat at low speed just until combined.
Beat 2 egg whites with a mixer at medium speed until soft peaks form. Add 2 tablespoons sugar, 1 tablespoon at a time, beating until stiff peaks form. Gently fold egg whites into the eggnog mixture. Pour filling into prepared crust. Bake at 325° for 40 minutes or until center is almost set. Cool completely on wire rack. Chill overnight.
To prepare bourbon cream, place the whipped topping in bowl. Gently fold in 2 tablespoons eggnog and bourbon; chill. Top each pie slice with bourbon cream; sprinkle with nutmeg before serving.