1. For the crispy layer: Line a 9-inch square pan with foil, leaving a 2-inch overhang on two sides. Lightly coat the foil and a wooden spoon with cooking spray.
2. Melt the butter in a medium saucepan over medium heat. Add the marshmallows, honey, vanilla and a pinch of salt, and stir with the prepared wooden spoon until the marshmallows have completely melted, 4 to 5 minutes. Add the rice cereal, and stir until the mixture is fully combined. Transfer the mixture to the prepared pan, and press into an even layer. Let sit at room temperature until firm, about 20 minutes.
3. For the cheesecake layer: Meanwhile, combine the gelatin with 2 tablespoons water in a small microwave-safe bowl, and set aside to soften, about 5 minutes.
4. Beat the cream cheese on medium-high speed in the bowl of a stand mixer fitted with a paddle attachment (or in a large bowl if using a hand mixer) until completely smooth, about 1 minute. Scrape down the sides of the bowl. Add the sour cream, sugar, lemon juice, vanilla and a pinch of salt, and beat on medium high speed until incorporated and smooth, about 1 minute.
5. Microwave the gelatin until melted, stirring as needed, about 30 seconds. Add the gelatin to the cream cheese mixture, and beat on medium high speed to combine, about 30 seconds.
6. To assemble: Pour the cream cheese-gelatin mixture over the cooled crispy layer, and spread out evenly. Wrap the pan loosely with plastic wrap, and refrigerate until the cheesecake layer is set, about 2 hours. (The bars can be assembled and refrigerated overnight.) Cut into 16 bars, and top each with raspberries and blueberries before serving.
Note: The cereal-and-marshmallow mixture will be sticky. Try wetting your hands before patting it down.