Prepare Raspberry Filling: In a medium saucepan over medium heat, combine water, raspberries, cornstarch, sugar, and lemon juice. Cook for about 5-7 minutes until thickened and raspberries break down. Cool completely.

Make the Crust: In a mixing bowl, combine melted butter, graham cracker crumbs, and sugar until moistened. Press into the bottom of a 9x13 inch baking dish. Bake at 350°F for 10 minutes. Cool.

Mix Cream Cheese Layer: Beat cream cheese and powdered sugar until smooth. Gradually add milk and vanilla until creamy. Fold in Cool Whip gently.

Assemble Layers: Spread the cream cheese mixture over the cooled crust. Spoon the raspberry filling over it, allowing it to swirl slightly.

Chill: Cover with plastic wrap and refrigerate for at least 6 hours or overnight to set the layers.