5tablespoons(65 grams) unsalted butter, cut into 6 pieces
Wash and dry the blueberries. Process them in a food processor. Pour the pureed berries into a 3-quart saucepan and add 2 tablespoons of lemon juice and 1/2 cup of sugar. Cook the berries over medium heat until the puree turns dark purple, and it has started to thicken, 10 minutes.
Strain the mixture into a medium-sized bowl through a fine mesh strainer to remove the blueberry skins. You should have about 1 cup of blueberry puree. Let the puree cool until it is just barely warm. While the puree is cooling clean the saucepan you cooked the berries in.
Pour the blueberry puree back into the saucepan. Clean the bowl and use it for the finished curd. Add the remaining lemon juice. Add the remaining sugar 2 tablespoons at a time. Whisk and taste after each addition until the desired sweetness is reached. The puree should still be a little tart.
Place a medium bowl with a fine-mesh strainer next to the stove. Add the whole eggs, and egg yolks to the saucepan and whisk to thoroughly combine. Place the pan over medium-low heat and whisk constantly, until the mixture is slightly thickened and registers 190°F.
Remove the pan from the heat and whisk in the butter one tablespoon at a time, only adding the next pat of butter when the previous is thoroughly incorporated.
Strain curd through the strainer into the bowl. Press a piece of plastic wrap directly onto surface of curd and refrigerate for at least 3 hours. The curd can be refrigerated for up to two weeks.
The sweetness of fresh blueberries can vary so you may need more or less sugar than the recipe calls for. Don't use more the 1-1/4 cups of sugar if adding additional sugar.