Preheat oven to 450°F. Melt butter in a 10-in. cast-iron or ovenproof skillet.
In a medium bowl, combine eggs, flour, milk, vanilla, salt, 1 Tbs. sugar, and cinnamon. Pour into skillet. Place skillet in oven. Bake 10 to 12 minutes or until puffed and brown. Remove from oven.
Top with berries and the remaining sugar. Bake about 5 minutes more. Remove from oven. Drizzle with lemon juice.
Cut into wedges; if desired, top with yogurt or lemon curd. Serve immediately.