For the i.c. mini cheesecake filling: Install an immersion circulator in a water bath and set it to 160ºF.
In the bowl of a stand mixer fitted with a paddle attachment, beat the cream cheese and sugar on high until fluffy, about 4 minutes. Scrape down the sides of the bowl with a rubber spatula after 1 minute.
Lower the mixer speed to medium and add the sour cream, lemon juice, and lemon zest, and continue beating until incorporated, about 30 seconds
Drop the speed to low and add the eggs one at a time, waiting 30 seconds between each egg. Mix until completely incorporated, about 1 minute more.
Fill ten 4-ounce glass canning jars with lids with the batter, leaving half an inch of headspace. Lid tightly and place in the water bath for 45 minutes.
Retrieve the jars from the water bath and cool for 1 hour at room temperature before refrigerating for at least 2 hours before serving.
For the i.c. mini cheesecake topping: Heat oven to 300ºF.
Pulse the crackers, sugar, and salt in the bowl of a food processor until they become coarse crumbs. Add the melted butter and pulse a few more times.
Pack the crumb mixture into an even layer on a parchment-lined quarter-sheet pan. Bake for 15 minutes. Cool and then crumble over cheesecakes before serving.