1cupfresh or frozen blueberries(if using frozen blueberries, do not thaw)
Instructions
Fill a large roasting pan about 2 inches deep with water. Place it on the lower middle oven rack and heat oven to 350°F. Lightly grease a 9x9" Pyrex baking dish or similar sized casserole dish.
In a large bowl, whisk together 3 large egg yolks, 1 teaspoon lemon zest, 1/4 cup lemon juice, 1 Tablespoon unsalted butter, and 1 teaspoon vanilla. In a medium bowl, whisk together 3/4 cup granulated sugar, 1/2 cup all purpose flour, and 1/2 teaspoon kosher salt.
Whisk half of the flour mixture into the egg yolk mixture, then whisk in 3/4 cup of the milk into the egg yolk mixture. Repeat with the remaining flour mixture and the remaining 3/4 cup of milk.
Using a hand mixer, whip 3 large egg whites on low speed until frothy (about 1 minute), then increase speed to high until stiff peaks form (about 2 more minutes). Gently fold the egg whites into the batter with a spatula until no more white streaks remain. Add 1 cup fresh or frozen blueberries and stir gently (they will sink to the bottom.
Pour batter into prepared baking dish and carefully place in the hot water bath. Bake until the top is set, about 45 minutes. Cool for at least 10 minutes before serving.