Place 16 oz. cream cheese out to soften. It should be about room temperature by the time you need it. Use a food processor to chop about 20 vanilla wafers until you have about 1½ cups of vanilla wafer crumbs once processed. In a mixing bowl, combine vanilla wafer crumbs with 6 tbsp. melted butter and 2 tbsp. white granulated sugar.
Pour the crumb mixture into the center of the tart tin. Spread evenly on the bottom of the tin and up the sides. You want to pack it very tightly. I used a measuring cup to press it firmly into the bottom. To line the edges nicely, I find it helps to wrap cellophane over the sides and pinch with my fingers to keep it from overflowing over the top. Once ready, refrigerate while you prepare the cheesecake filling.
Add 1 cup heavy whipping cream and 2 tsp. cornstarch to a food processor (you could also use a hand mixer in a mixing bowl, or standing mixer, but it may splash out of the bowl a bit). Process on a puree setting until the cream stops splashing inside. This could take about a minute or a bit longer.
Add whipped cream to a mixing bowl (or standing mixer with beaters) with softened cream cheese, 2 tsp. fresh lemon juice, 1 tsp. real vanilla extract, and ½ cup sugar. Use a hand mixer on medium speed to thoroughly mix ingredients. Remove tart tin from the refrigerator. Spoon the cheesecake mixture into the crust, gently pushing it to the edges but not up the sides. Cover with cellophane and refrigerate. There should be a little room on top for your compote.
Create the blackberry Sorel compote. Add 12 oz. blackberries (about 2 standard packages) to a saucepan with 2 tbsp. Sorel Liqueur and 1 tbsp. white granulated sugar. Simmer over MEDIUM-HIGH heat for 20 minutes, stirring occasionally, and breaking the berries up a bit. After 20 minutes, add 1½ tsp. minute tapioca and 1 tsp. lemon juice. Stir briefly, and refrigerate until cool. About 30 minutes.
Once the compote is cool, add 1 more tbsp. Sorel Liqueur, stir and remove the cheesecake from the refrigerator. Spoon compote over top, gently guiding it all the way to the edges. Refrigerate cheesecake for at least 4 hours to allow it to set. Optionally garnish with black and blueberries, and serve.