Whisk eggs together. Add flour, 1 tablespoon sugar, baking powder, and salt. Gradually mix in milk, stirring constantly. Add vanilla, 2 tablespoons melted butter, and ½ teaspoon cinnamon. Let batter stand for 30 minutes. This step is very important.

Preheat the oven to 425° F while batter is resting.

Melt 4 tablespoons butter in a 10-inch oven-proof skillet. (A well-seasoned cast iron pan works great for this.) Brush butter up on the sides of the pan. Combine ¼ cup brown sugar and other ½ teaspoon of the cinnamon in a small bowl. Sprinkle sugar mixture over the butter. Lay apple slices evenly around pan. Sprinkle remaining ¼ cup brown sugar over apples. Place pan over medium-high heat until the mixture bubbles, then gently pour batter mixture evenly over apples.

Bake in preheated oven for 15 minutes. Reduce heat to 375° F and bake for 8-10 minutes more until pancake is puffed up and starting to brown. Cut into wedges. Serve immediately.

Serve with syrup, powdered sugar, and fresh fruit if desired.