Whisk cornstarch and cold water together in a small bowl until fully dissolved. Pour into the raspberry mixture while stirring, then increase the heat to medium and return to a simmer. Cook for 1 to 2 minutes until slightly thickened. Remove from heat.

Strain the sauce immediately through a fine mesh strainer into a heatproof bowl, pressing firmly with a spatula to extract as much liquid as possible. Discard the solids. Set aside to cool to room temperature.

Preheat oven to 350°F. Wrap the outside of each 4-inch springform pan thoroughly with 3 layers of heavy-duty aluminum foil, ensuring the foil comes up the sides of the pan. Spray the inside of each pan with nonstick cooking spray.

Combine graham cracker crumbs and sugar in a bowl and stir to combine. Add melted butter and mix with a fork until the texture resembles wet sand. Divide the mixture evenly among the five pans and press it firmly into the bottoms and slightly up the sides. Bake for 10 to 12 minutes until the edges begin to lightly brown. Transfer to a wire rack and cool completely. Reduce oven temperature to 325°F.

Beat cream cheese, sugar, and flour on medium speed until smooth and combined, about 1 minute. Scrape down the sides and bottom of the bowl. Add sour cream, vanilla, and salt, and beat on low until just combined. Add eggs one at a time on low speed, mixing just until each is incorporated. Scrape the bowl between additions. Do not overmix.

Divide the batter evenly between the five pans, filling each about 3/4 full. Add three to four small dots of raspberry sauce to the surface of each cheesecake, using about 1 teaspoon of sauce per dot. Use a toothpick or skewer to gently swirl the sauce through the batter. Reserve the remaining sauce, covered, in the refrigerator for serving.

Place the foil-wrapped pans into a large roasting pan, spacing them slightly apart so water can circulate around each one. Place the roasting pan on the center oven rack. Carefully pour hot water into the roasting pan until it reaches halfway up the sides of the springform pans.

Bake at 325°F for 25 to 30 minutes, until the outer 2 to 3 inches appear set and the center has a controlled wobble when the pan is gently shaken.

Turn off the oven and crack the door open about 1 inch. Leave the cheesecakes in the water bath in the oven for 1 hour.

Remove the roasting pan from the oven. Carefully lift each cheesecake out of the water bath, remove the foil, and place it on a wire rack. Run a thin paring knife around the edge of each cheesecake to loosen it from the pan.

Cool at room temperature for 2 hours, then cover and refrigerate for at least 8 hours or overnight before serving. Serve with reserved raspberry sauce drizzled over each cheesecake.