Place the blueberries and water in a small saucepan over low to medium heat. Cook until the mixture begins to simmer and the blueberries begin to pop. Remove from heat, and strain through a mesh sieve. Allow the mixture to cool to slightly.

Place 1 to 2 inches of water into a double boiler, or make a double boiler out of a saucepan and a heat-safe bowl. Bring the water to a boil, then reduce to a simmer.

Place egg yolks, whole egg, granulated sugar, lemon zest, and lemon juice, into the top pot of the double boiler or bowl over the pan.

Whisk constantly while the curd cooks to ensure the eggs don’t scramble. The mixture will begin to thicken. After about 10 minutes, the mixture should resemble the texture of hollandaise sauce. Remove from heat, and whisk in the butter.

After the butter melts, stir in the blueberry mixture. Pour the mixture into a sealable container, and cover with plastic wrap making sure that the plastic wrap touches the curd.

Refrigerate for 2 to 3 hours until completely chilled. Serve on toast, pancakes, English muffins, pound cake, Angel food cake, or your other favorite desserts. Store leftovers in the refrigerator for up to 7 days.