For the 6 Inch Cheesecake

• Prep the oven. Position a rack in the center of the oven and preheat the oven to 350°F.
• Make the crust. In a medium bowl, combine the graham cracker crumbs, melted butter, and salt. Toss with your fingers until the mixture looks like wet sand. Pour the mixture into the springform pan and use a tart tamper or your hands to press it evenly over the bottom of the pan, all the way to the edges. (You can use the bottom of a coffee mug or heavy glass to pound the crumbs in place—you want to apply some pressure here so that the crust holds its shape.)
• Bake the crust. Bake for 8 minutes. The crust will look underbaked and feel soft to the touch when you remove it from the oven, but will firm up as it cools. Set on a wire rack to cool slightly while you make the filling.
• Make the filling. In the bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese on medium until soft and creamy, about 4 minutes. Add the sugar and salt and beat until light and fluffy, about 1 minute, using a rubber spatula to scrape down the bottom and sides of the bowl as necessary. Reduce the mixer to low and add the eggs one at a time, adding the next egg only after the previous one is fully incorporated, scraping down the bottom and sides of the bowl after each addition. With the mixer on low, add the cream and vanilla all at once and beat until combined, about 1 minute. Scrape down the bottom and sides of the bowl once more, and beat on medium for an additional 30 seconds.
• Assemble for baking. Pour the filling over the crust and use an offset spatula to smooth the top. Tightly wrap the bottom of the springform pan with two layers of aluminum foil. Place in the center of a 9 x 13-inch cake pan or roasting pan. Pour boiling water into the pan until water reaches halfway up the sides of the springform pan.
• Bake the cheesecake. Bake for 90 minutes, or until the edges of the cheesecake are set but the center still wobbles slightly. Check the cheesecake at 60 minutes. The outer edges of the cheesecake should be starting to set. If the edges are completely set, check for doneness again in 5 or 10 minutes. If the top of the cheesecake is starting to brown too much, tent the top of the springform pan with a loose sheet of aluminum foil.
• Cool the cheesecake. Once the cheesecake is done, turn off the oven's heat. Open the oven door just a crack, propping it open with a heatproof cooking utensil like a wooden spoon. Leave the cheesecake in the water bath in the oven for 30 minutes. After 30 minutes, remove the cheesecake from the oven and place on a wire rack. Run a butter knife or offset spatula around the edge of the pan to loosen the cheesecake. Cool the cheesecake completely in the springform pan on the wire rack.
• Make the sour cream topping. Once the cheesecake is completely cool, make the sour cream glaze. In a small bowl, whisk together the sour cream and sugar for the topping.
• Finish assembling the cheesecake. Pour the topping over the cheesecake and use an offset spatula to smooth it across the cheesecake's top.
• Chill the cheesecake. Cover the top of the springform pan loosely with plastic wrap and refrigerate until the cheesecake is firm, at least 4 hours, preferably overnight.
• Serve and store. To serve, unlatch the springform pan and lift the sides of the pan away from the bottom of the pan. Use a hot knife to slice and serve. Serve chilled from the refrigerator. Leftover cheesecake slices can be stored in an airtight container in the refrigerator for up to 5 days.