For the meringue, in a large glass, metal or ceramic bowl (don't use plastic), beat the egg whites with the cream of tartar and salt until foamy. While beating at high speed, gradually add the sugar one tablespoon or so at a time until it has been incorporated. Continue beating until the whites form stiff peaks. Don't underbeat or the meringue won't set up correctly.
Lightly grease a 9X13-inch baking pan. Spread the meringue mixture evenly into the pan. Bake for 1 hour. Turn the oven off and let the pan of meringue sit in the oven overnight (or for 10-12 hours).
For the berry topping, in a medium saucepan, combine the cherries, sugar, water, lemon juice and cornstarch.
Over medium-low heat, bring the mixture to a simmer and cook for 10-20 minutes until slightly thickened. Pour the mixture into a bowl and let cool at room temperature for 20-30 minutes.
Stir in the sliced strawberries. Cover, and refrigerate until fully chilled.
At least 4-6 hours before serving, remove the meringue from the oven.
For the cheesecake layer, in a medium bowl, whip the cream cheese, powdered sugar and vanilla together until smooth. Pour in the whipping cream and starting on low speed (so the cream doesn't splatter everywhere), whip the mixture together until it is thick and fluffy, 5-7 minutes. Spread the cream cheese topping over the cooled meringue.
Cover and refrigerate for at least 4 hours or up to overnight.
When ready to serve, cut the dessert into pieces and top with a spoonful of the berry mixture.
Notes
Make Ahead: the meringue can be made 2 days in advance, topped with the cream cheese filling up to 24 hours in advance and refrigerated and the berry mixture can be made one day ahead also. Cornstarch: the fruit sauce, as written in the recipe, is on the thin side. For a thicker sauce, increase the cornstarch to 1 1/2 to 2 tablespoons.