Preheat the oven to 425˚F and heat a 10-inch cast-iron skillet (or oven ready skillet) over moderate heat.
In a medium bowl, whisk the eggs with the finely grated lemon zest and sugar until combined. Add the flour and milk and whisk until smooth. Add 1 cup of your favorite berries.
Melt the butter in the skillet and add the pancake batter, spreading the fruit evenly. Bake in the center of the oven for about 22 minutes, or until the edges are browned and puffed and the center is lightly toasted in spots.
Transfer the skillet to a trivet and dust with confectioner's sugar. Cut the wedges and serve with the remaining fresh berries.
Notes
Without Berries: Berries create a very moist German pancake. If you prefer a crispier texture, bake without the berries and use them as a topping instead.