Preheat the oven to 425 degrees.

Gently combine the berries and sugar in a small bowl and set aside while you make the pancakes. Place 4 (6- to 7-inch) individual gratin dishes on two sheet pans. Place 1 teaspoon of butter in each gratin dish and set aside.

Place the eggs in the bowl of an electric mixer fitted with a whisk attachment and beat on medium speed until mixed. Add the milk and combine. Slowly add the flour, vanilla, orange zest, 2 tablespoons melted butter, and the salt and mix just until smooth. Whisk by hand if the mixture is lumpy.

Place the gratin dishes in the oven for 3 minutes, until the butter is hot and bubbly. Make sure the butter covers the bottom of each dish. Immediately divide the batter equally among the gratin dishes and bake for 12 to 14 minutes, until puffed and lightly browned. Divide the berries among the dishes, drizzle with maple syrup, dust with confectioners' sugar, and serve hot.