
Butter a 13 x 9" baking dish. Preheat the oven to 275℉.
Using a chilled bowl and chilled beaters, beat the egg whites and cream of tartar until foamy. Slowly beat in 1 3/4 cups of sugar (add it in 1 Tablespoon at a time) until the egg whites are still and flossy. Spread the meringue in the pan and place in the oven. TURN OFF THE OVEN! And leave the pan in oven for 12 hours or longer. DO NOT OPEN THE OVEN DOOR FOR THOSE 12 HOURS.
The next day, using a chilled bowl and beaters, beat at the heavy cream until it's stiff. Beat in the cream cheese, vanilla and 1 cup sugar. Once it's well blended, spread it over the meringue. Chill for another 12-24 hours.
Meanwhile, in a large bowl, mix together the can of cherry pie filling, lemon juice, fresh strawberries, and fresh blueberries, and fresh blackberries.
Cut the cake into 15 pieces and serve with the berry sauce on top.