3 large eggs
1/2 cup milk
1 medium lemon
2 T sugar, granulated
1 t vanilla
3/4 teaspoon kosher salt
1/2 flour
3 T unsalted butter
3/4 cup fresh or frozen blueberries (do not thaw)
Instructions:
Place 3 large eggs and 1/2 cup milk on the counter and let come to room temperature, about 30 minutes. Meanwhile, arrange a rack in the middle of the oven and heat to 450.
Finely grate the zest of medium lemon into a medium bowl (about 1 tablespoon). Add 2 tablespoons granulated sugar and use your fingers to rub the zest into the sugar to release the oil. Add the eggs, milk, 12 teaspoon vanilla, and 1/4 teaspoon kosher salt, and whisk to combine. Add flour and whisk until smooth. (alternately, place all the ingredients in the blender and blend until smooth, about 10 seconds.
Melt 3 tablespoons unsalted butter in a 10 inch cast iron skillet over medium heat. Add 3/4 cup blueberries. Cook stirring occasionally, until they swell and begin to pop, 1 to 2 minutes. Remove the skillet from the heat. Spread the blueberries into a single layer. Pour the batter evenly over the blueberries.
Transfer the skillet to the oven and bake until set in the center and puffed around the edges, 12-15 minutes.