Step 1: Prepare the Crust

1. Preheat your oven to 325°F (160°C) and line a 12-cup muffin tin with paper liners.
2. In a medium bowl, combine graham cracker crumbs, sugar, and melted butter. Mix until the texture resembles wet sand.
3. Spoon about 1 tablespoon of the mixture into each muffin cup, pressing down firmly with the back of a spoon or a flat-bottomed glass.
4. Bake the crusts for 5 minutes, then set aside to cool while preparing the filling.

Step 2: Make the Cheesecake Filling

1. In a large mixing bowl, beat the cream cheese and sugar together with an electric mixer until smooth and creamy.
2. Add the eggs, one at a time, mixing well after each addition.
3. Mix in the sour cream, lemon juice, lemon zest, and vanilla extract until fully incorporated.
4. Divide the cheesecake filling evenly among the muffin cups, filling each about 3/4 full.

Step 3: Bake the Cheesecakes

1. Bake in the preheated oven for 18-20 minutes, or until the centers are just set.
2. Remove from the oven and allow the cheesecakes to cool in the pan for 30 minutes.
3. Transfer to the refrigerator and chill for at least 2 hours, or until completely cold and firm.

Step 4: Prepare the Lemon Curd Topping

1. In a small saucepan, whisk together the egg yolks, sugar, and lemon juice.
2. Cook over medium heat, stirring constantly, until the mixture thickens enough to coat the back of a spoon (about 5 minutes).
3. Remove from heat and stir in the butter and lemon zest until smooth.
4. Allow the lemon curd to cool completely before spooning it onto the chilled cheesecakes.

Step 5: Garnish and Serve

1. Add a dollop of whipped cream, fresh berries, or a lemon slice on top of each mini cheesecake for an extra touch of elegance.
2. Serve chilled and enjoy!