For the Blueberry Sauce:

1. In a medium-sized saucepan, combine blueberries, sugar, flour, and lemon juice; stir well. Cook over medium-high heat until mixture starts to bubble, stirring often. Turn down the heat and let simmer to allow the blueberries to soften.
2. Cook until sauce thickens; about 10-15 minutes. Stir often so the bottom does not burn. Allow to cool for 20 minutes, refrigerate if necessary.

For the Cheesecake Filling:

1. Place the mixing bowl and whisk attachment in the freezer for 5 to 10 minutes to chill.
2. Prepare the whipped cream. Pour the heavy whipping cream into the chilled bowl and use an electric mixer to beat the heavy cream on high speed until stiff peaks form. Add the powdered sugar and continue beating on high speed until stiff peaks form. Set the whipped cream aside.
3. Beat the softened cream cheese until it’s completely smooth. Scrape down the sides of the bowl as needed. Next, add the granulated sugar and lemon zest and continue beating until smooth and free of lumps. Fold the prepared whipped cream into the cream cheese, stirring until well combined.

To Assemble the Icebox Cake,

1. In a 9-inch square pan, lay a piece of parchment paper on the bottom. Lay out the graham crackers to cover the bottom of the pan so there are as many large pieces as possible. For one edge, you will need to break the graham crackers apart or cut them with a serrated knife.
2. Spread half of the cheesecake filling over the bottom layer of the graham crackers.  Then spread half the blueberry sauce over the cheesecake. Repeat these steps one more time, layering the graham crackers, remaining cheesecake filling and blueberry sauce. Top with a layer of graham crackers.

For the Topping:

1. Prepare the second batch of whipped cream as instructed above. Spread over the top of the graham crackers.
2. Refrigerate for 3-4 hours. Garnish with any leftover berries or slices of lemon.