Preheat the oven to 325°F (163°C) and line a muffin tin with cupcake liners.
In a bowl, mix the graham cracker crumbs, sugar, and melted butter until well combined.
Press about 1 tbsp of the mixture into each cupcake liner and bake for 5 minutes. Let cool.
In a mixing bowl, beat the cream cheese and sugar until smooth.
Add the egg, vanilla extract, lemon zest, and lemon juice, and mix until well combined.
Fold in the sour cream, then divide the batter evenly among the liners.
Bake for 18-20 minutes until the centers are set.
Allow the cheesecakes to cool at room temperature, then chill in the refrigerator for at least 2 hours.
Top with whipped cream and fresh lemon slices before serving.