To Make the Sauce:

1. In a medium saucepan over medium heat, combine the berries, sugar, and lemon zest.
2. Cook the berries, stirring frequently, until the mixture comes to a simmer.
3. Continue to cook, stirring frequently, until the berries have broken down and sauce is thickened, 4 to 5 minutes.
4. Pour the mixture into a fine mesh sieve set over a bowl, and press the raspberry purée through with a spatula. You should have about 3/4 cup of raspberry purée sauce.
5. Disgard the seeds and chill the purée while you prepare the rest of the cheesecake.

To Make the Crust:

1. Add the graham crackers sheets to the bowl of a food processor fitted with the blade attachment and pulse until you have fine crumbs. You will end up with about 1 3/4 cups. You can also make the crumbs in a Ziplock bag. Just add the sheets to the bag, seal it, and crush the crackers until you get crumbs.
2. Pour the crumbs into a bowl (or leave them in the bowl of the food processor), and add the butter, sugar and salt, and stir or pulse until the butter is evenly distributed and the crumbs are moistened.
3. Spray the inside of the mini tart pans with cooking spray, and divide the crumb mixture evenly between the pans.
4. Use a measuring cup, firmly press the mixture into the bottom and up the sides of the mini tart pans. Use your fingers to press the mixture into the fluted edges, if necessary.
5. Refrigerate the crusts while you make the filling.

To Make the Filling: 

1. In the bowl of a stand mixer fitted with the whisk attachment, combine the cream cheese, sugar, lemon zest and juice, vanilla extract and salt.
2. Mix on low speed until combined.
3. Then, turn the mixer up to medium and beat until smooth and fluffy, about 2 minutes.
4. Stop the mixer and scrape the bottom and sides of the bowl to ensure even mixing. Then add the sour cream and stir until just combined.
5. With the mixer on low speed, slowly pour in the cream. Turn the speed up to high and whip until thick and fluffy, about 5 minutes, stopping to scrape the bottom and sides of the bowl, as needed.
6. Pour the mixture into the prepared crusts and use an offset spatula to smooth the top.
7. Dot the top with the chilled raspberry purée.
8. Using a paring knife or a wooden skewer (or toothpick), swirl the purée into the cream cheese mixture.
9. Chill at least 8 hours and up to overnight.
10. Serve cold (in or out of their pans) with fresh raspberries and any leftover raspberry purée, if desired.