1. Center a rack in oven and heat to 275 degrees. Grease a 9" glass pie dish with butter and set aside.
2. To make the crust, beat egg whites in a large bowl with an electric mixer on low until foamy. Increase speed to medium and beat until soft peaks form. Add cream of tartar and salt and continue beating, adding 3/4 cup sugar a few tablespoons at a time, until stiff peaks form.
3. Pour beaten egg whites into prepared pie dish and use a rubber spatula to spread into an even layer. Make an indent about 4" wide in center of pie dish (this will allow mixture to form an even meringue crust when baked). Transfer to oven and bake 25 minutes, then increase oven temperature to 300 degrees and bake 25 more minutes. Let crust cool completely at room temperature, about 1 hour.
4. To make the filling, grate peel from lemons and set aside. Squeeze 1/3 cup plus 1 tablespoon juice from lemons into a small bowl and set aside. Whisk egg yolks in a medium saucepan until thick and pale yellow. Stir in 3/4 cup sugar and the lemon zest and juice and cook over medium heat, stirring constantly, until slightly thickened, 5 to 7 minutes. Transfer filling to a large bowl and let sit until completely cooled, at least 1 hour.
5. When filling has cooled, beat 1 cup heavy cream in a separate large bowl with an electric mixer on medium-high until soft peaks form. Gently fold whipped cream into lemon filling and pour into cooled crust.
6. Combine remaining 1 cup heavy cream, remaining 2 tablespoons sugar, and the vanilla in now-empty bowl and beat until soft peaks form. Spread over top of pie and chill until set, at least 12 hours and up to one day.
Source: Hannaford fresh Magazine, May - June 2019