Preheat oven to 325°F. Lightly grease a mini cheesecake pan with 12 wells, or line cupcake pan with paper liners.
For the crust, combine the graham cracker crumbs, melted butter and sugar. Press a heaping tablespoon into the bottom of each cup and tamp down firmly.
In a stand mixer, beat the cream cheese and sugar until smooth. Add the egg, cream and vanilla; mix on low speed until combined. Evenly divide the mixture among the cheesecake pan.
In a microwave safe bowl, warm the guava paste until melted, but not hot. Add lemon juice to thin it out and stir to combine.
Place a half teaspoon of guava paste on each cheesecake and swirl with a toothpick. Bake for 15-18 minutes, or just until set. Let cool on a wire rack before removing from pan, then chill cheesecakes thoroughly before serving.
Notes
You can also use guava preserves or preserves of choice in place of guava paste.