Scatter the blueberries on a clean kitchen towel so they are very dry.

Fill a medium saucepan one-third to one-half full with water and bring to a gentle simmer. Whisk together the egg yolks, sugar, lemon juice, and lemon zest in a metal bowl that will fit over the saucepan. Set the bowl in the saucepan and stir or whisk continuously until the mixture starts to thicken. Remove from the heat and let cool.

In a large bowl, beat the egg whites to soft peaks and set aside. In another bowl, beat the cream to stiff, but not dry, peaks and set aside.

Gently fold the whipped cream into the cooled egg yolk mixture, until well incorporated. Then fold that mixture into the egg whites until well incorporated. Cover the mousse with plastic wrap and refrigerate until chilled and ready to serve, at least 1 hour.

Divide the mousse among 6 to 8 dessert bowls and scatter the blueberries on top.