Prepare the molds: Place six mini dessert molds on a flat tray. Add narrow strips of parchment paper to make the cheesecakes easier to remove. Alternatively, line a muffin pan with paper liners.
Bloom the gelatin: Place the powdered gelatin in a small bowl and add 2 tablespoons of cold water. Let it stand for 5-10 minutes, or until fully bloomed.
Make the raspberry topping: Add the raspberries and sugar to a small saucepan. Cook over medium-low heat until the fruit releases its juices and begins to simmer.
Thicken the topping: Whisk the cornstarch with 4 tablespoons of cold water until smooth. Pour it into the simmering raspberries while stirring. Cook over low heat until thickened, then remove from the heat and let it cool completely.
Prepare the crust: Combine the graham cracker crumbs and melted butter. Divide the mixture evenly among the molds and gently press it into a firm, even layer. Refrigerate while preparing the filling.
Whip the cream: Beat the cold heavy whipping cream until firm peaks form. Be careful not to overwhip it. Set aside.
Mix the cream cheese: In a separate bowl, beat the softened cream cheese, sweetened condensed milk, and vanilla extract until smooth.
Combine the filling: Add the cream cheese mixture to the whipped cream and gently fold with a spatula until evenly combined.
Melt the gelatin: Microwave the bloomed gelatin for 10-15 seconds, just until completely melted. Do not allow it to boil. Gradually add it to the cheesecake filling while gently mixing until smooth.
Make the berry filling: Divide the cheesecake filling into two equal portions. Leave one portion plain and fold 1-2 tablespoons of the cooled berry topping into the other portion.
Assemble the cheesecakes: Spoon the plain filling over the prepared crusts, filling each mold halfway. Add the raspberry cheesecake filling and smooth the tops.
Add the topping: Spoon a thin, even layer of the remaining raspberry topping over each mini cheesecake.
Chill: Refrigerate for at least 4 hours or, preferably, overnight, until completely firm.
Decorate and serve: Carefully remove the cheesecakes from the molds. Decorate with fresh raspberries, blueberries, or other berries and serve chilled.