Finely crush the biscuits and moisten with the melted butter. Divide between 6 small oven dishes or large muffin tins, pressing it firmly into the base. Place in the refrigerator to chill.
Heat the oven to 160˚ C.
Combine the eggs, citrus zest and juice, cream cheese and sugar in a food processor and process to a creamy consistency.
Pour over the biscuit bases and place in the oven to bake for about 25 minutes, or until the cheesecakes are cooked through and very lightly golden on top. Let cool in their dishes, and then run a knife around each cheesecake and turn out onto a plate. Turn right side up, cover with plastic wrap and chill.
To make Lemon Curd, beat 3 tablespoons softened unsalted butter with ½ cup sugar until smooth and creamy. Add 2 egg yolks and 1 whole egg and beat for 1 minute. Add 1/3 cup lemon juice, beating well. The mixture will look curdled, but don’t worry. Tip into a saucepan and cook over low heat until smooth, whisking continually, then increase the heat to medium-low and continue to cook until it thickens and becomes less opaque, about 8 minutes, stirring slowly. Add lemon zest at the end.