Preheat oven to 275°F. Butter a 13”x9” pan.
In a large bowl with an hand electric mixer or stand mixer, beat egg whites on high speed until foamy. Add salt, cream of tartar and sugar and beat until stiff and glossy, about 15 minutes. Spread in the prepared pan and bake for 1 hour. DO NOT open the oven door. Leave the baked crust in the oven overnight. If the crust settles, it’s totally ok!
Next day, whip whipping cream on with an electric mixer or stand mixer on high speed until stiff peaks form. Set aside.
In a separate bowl, beat room temperature cream cheese, sugar and teaspoon of vanilla on medium speed until smooth.
Gently fold the whipped cream into the cream cheese mix ⅓ at a time.
Fold in the marshmallows.
Pour the mixture over the crust and spread evenly to the edges.
In a medium bowl, combine the cherry pie filling, pint of fresh sliced strawberries, and teaspoon lemon juice. Pour over the filling and evenly spread to the edges.
Last step, chill at least 4 hours in the refrigerator before serving. Slice individual portions of the dessert with a knife and serve with a spatula. Garnish if desired.