Preheat the oven to 350°F (180°C). Line a mini muffin tin with paper liners.
In a small bowl, mix graham cracker crumbs, sugar, and melted butter until well combined. Press a tablespoon of the mixture into the bottom of each muffin cup.
In a large bowl, beat cream cheese, sugar, and vanilla extract until smooth. Add the egg and mix until just combined.
Fill each muffin cup with the cream cheese mixture almost to the top.
In a small saucepan, combine rhubarb, sugar, and water. Cook over medium heat until the rhubarb breaks down and the mixture thickens into a swirlable consistency.
Drop a small spoonful of the rhubarb mixture onto the top of each cheesecake bite and swirl with a toothpick.
Bake for 15-18 minutes or until the cheesecake is set. Let cool completely before serving.
Refrigerate any leftovers in an airtight container.