Lemon-Buttermilk Icebox Pie

Preheat oven to 325°F. Whisk together first 3 ingredients in a bowl.

Beat egg yolks with a handheld mixer in a medium bowl at high speed 4 to 5 minutes or until yolks become pale and ribbons form on surface of mixture when beater is lifted. Gradually whisk in sweetened condensed milk mixture, and whisk until thoroughly combined; whisk in buttermilk. Pour mixture into prepared crust.

Bake at 325° for 20 to 25 minutes or until set around edges. (Pie will be slightly jiggly.) Cool on a wire rack 1 hour. Cover pie with lightly greased (with cooking spray) plastic wrap, and freeze 4 to 6 hours.

Optional: Bring 1 cup blueberries, sugar, water, lemon juice, and lemon zest to a boil in a small saucepan over medium-high heat. Reduce heat to low, and simmer, stirring occasionally, 8 to 10 minutes or until mixture has thickened and berries begin to break down. Remove from heat, and stir in remaining 1 cup blueberries. Cool completely (about 1 hour); cover and chill until ready to use.

Top pie with Lemon-Blueberry Topping just before serving, if desired.