RITZ Mock Apple Pie

Heat oven to 400ºF. Make filling: Mix water, granulated sugar and cream of tartar in large saucepan. Bring to boil on medium-high heat. Add crackers; simmer on medium-low heat 5 min., stirring occasionally. Line 9-inch pie plate with crust as directed on package; fill with cracker mixture. Sprinkle with lemon juice and cinnamon. Make topping: Combine all topping ingredients. Bake 10 minutes at 400, reduce to 350 and cover edges of pie crust with foil. Bake 18-20 more minutes, or until pie filling has set. It shouldn't jiggle a lot when moved. Cool before serving.