To make the crust: Blend together the graham cracker crumbs and sugar. Place 2 tablespoons in the bottom of each of seven 1/2-pint canning jars, such as Mason jars. Press down lightly. Set the jars aside.
To make the batter: Place the softened cream cheese into the bowl of your mixer. Beat on medium-high speed for 2 minutes, to aerate and remove any lumps. Be sure to scrape the bowl at least twice.
Stop the mixer, scrape the bowl, and add the sugar and cornstarch. Beat on medium speed for 2 more minutes. Stop again, scrape, and add the vanilla, eggs, and cream. Beat for 2 more minutes on low speed.
Prepare a 7- to 8-quart slow cooker for baking. Place the crust-filled jars into the pot. Fill each jar 3/4 full of cheesecake batter, taking care not to drip any down the outsides of the jars.
Place the canning lid of each jar on lightly. This is to prevent water from dripping into the cheesecake while you fill the crock pot. Carefully pour warm water into the crock pot around the jars. The water level should come 3/4 of the way up the sides of the jars. When you're done pouring, remove the jar lids and set aside for later.
Cover the slow cooker and cook on high for 1 to 2 hours. All slow cookers are different, so the times may vary quite a bit. The cheesecakes are done when the centers are no longer jiggly or wobbly, and a knife inserted into the cake about 1/2" from the edge comes out clean.
Turn off the slow cooker and allow the cheesecakes to rest for about 20 minutes to cool slightly before handling. Remove the jars and place on the counter to cool for another hour before sealing and placing in the fridge to chill for several hours, or overnight.
To serve, simply open the jar, top with fresh berries, chocolate chips, hot fudge, or whipped cream, and dive in with a long-handled spoon. These are very rich cakes, so one jar will feed two people; or any leftovers can be refrigerated for serving later.