Preheat the oven to 400°F (200°C).

In a blender or with a hand mixer, combine 4 large eggs, 1 cup whole milk, 1 cup all purpose flour, 1/4 cup granulated white sugar, 1/2 teaspoon freshly grated lemon zest, and 1/4 teaspoon salt; blend or beat until the batter is smooth and free of lumps. Scrape down the sides as needed.

Place a 12-inch cast iron skillet on the stove over medium-high heat. Add 2 tablespoons unsalted butter and heat until the butter is melted and foamy, coating the bottom and sides of the skillet.

Pour the batter into the hot skillet, tilting the skillet if needed to evenly distribute the batter.

Immediately scatter 1/2 cup blueberries and 1/2 cup halved raspberries evenly over the batter.

Transfer the skillet to the preheated oven and bake until the pancake is well puffed, the edges are golden, and the center is set, about 20 minutes.

Remove the skillet from the oven and let the pancake cool for 2–3 minutes. Slice and serve topped with powdered sugar, syrup and/or freshly whipped cream as desired.