Make the Lemon Curd: Beat the granulated sugar and butter in a large bowl with an electric mixer at medium speed until fluffy, about 2 minutes. Add the eggs and the egg yolks; beat until combined, about 1 minute. Add the lemon juice; beat until combined, about 1 minute (the mixture will look curdled). Pour the mixture into a medium heavy-bottomed saucepan; cook over low until smooth, about 2 minutes. Increase the heat to medium; cook, stirring constantly, until the mixture coats the back of a spoon, 5 to 7 minutes. (Do not let the mixture come to a boil.) Remove from the heat; stir in the zest. Transfer the mixture to a shallow dish. Place plastic wrap directly on the warm curd (to prevent a film from forming); chill until cold, about 2 hours.

Make the Pancake: Place a medium cast-iron skillet in the oven; preheat the oven to 425°F. (Do not remove the skillet while the oven preheats.) Process the flour, milk, eggs, granulated sugar, zest, vanilla, and salt in a blender until smooth and slightly foamy, about 1 minute. Remove the skillet from the oven; melt the butter in the skillet and tilt in all directions to coat the bottom of the skillet. Pour the batter into the skillet; bake until puffed and golden, about 10 minutes. Reduce the temperature to 300°F, and bake until set, about 8 minutes. Remove from the oven. Sprinkle with the powdered sugar. Top with the Lemon Curd and fresh berries. Serve immediately.