Make the Pie Filling:

1. Add blueberries, sugar, cornstarch, cinnamon and salt to a medium pot and mix together until combined.
2. Turn the heat on to medium and cook, stirring frequently until the filling is bubbling throughout, about 5-8 minutes.
3. Remove from the heat, and transfer to a heat proof container to cool down to room temperature.

Make Cream Filling:

1. With an electric mixer using the whisk attachment, whip the heavy cream until medium-stiff peaks form, about 3 minutes. Remove the whipped cream from the bowl and set aside in a separate bowl.
2. Place the mascarpone in the now empty mixing bowl, along with the sugar, vanilla, cinnamon, and salt. Whip on medium speed until completely smooth, about 2 minutes, scraping down the bowl halfway though.
3. Fold in ⅓ of the whipped cream to the mascarpone mixture with a rubber spatula until it is completely combined.
4. Add the remaining whipped cream to the bowl and gently fold it in, being careful not to deflate it. Transfer about 1 cup of the mascarpone filling to an airtight container and place in the refrigerator until the cake is ready to be served. It will be used for decorating the top of the cake.

Assemble:

1. Line a 9” square baking dish (see note about other containers) with 2 pieces of parchment paper to create a sling to remove the finished cake. Make sure to leave some overhang to easily pull up and release the cake later.
2. Line the entire bottom of the prepared pan with graham crackers, cutting any crackers as needed so they fit snuggly in one layer.
3. Spread half of the mascarpone filling evenly on top of the graham crackers.
4. Spread half of the cooled blueberry pie filling evenly on top of the mascarpone.
5. Place another layer of graham crackers on top of the blueberries.
6. Repeat the process with one more layer of mascarpone, and blueberry pie filling.
7. Place the final half layer of graham crackers on top of the blueberry filling. It is only half so the cake can be cut in half and stacked later. If you don’t plan to stack the cake, you can put graham crackers to cover.
8. Cover the dish and let rest in the refrigerator for 8-12 hours.
9. Transfer the dish to the freezer to let chill for at least 1 hour before ready to assemble.
10. Once ready to assemble, remove from the freezer. Run a hot and dry butter knife along the edges of the cake, to help release the sides from the pan. Then carefully lift the cake out of the pan.
11. Place cake on a cutting board and cut in half along the edge of the graham crackers. Carefully place the half with the graham cracker on top of the layer with the blueberry filling so you have tall loaf cake.
12. Place the cake on a platter and spread the reserved mascarpone filling on the top layer. Decorate as desired with fresh blueberries.
13. Let the cake sit for 5-10 minutes to soften up, and then slice and serve. Or, place in the refrigerator until ready to serve.