Preheat the oven to 425 degrees Fahrenheit.
Peel, core and thinly slice your apples.
Melt 6 Tbsp (¾ stick) of butter in a skillet. Add apple slices and mix in ¾ cup of brown sugar and 2 tablespoons of cinnamon. Mix on medium low simmer until apples have softened 5- 10 minutes.
Whisk eggs in a small bowl until smooth. Then add whisked eggs to a large bowl and whisk in milk, sugar, vanilla, salt, and 1 teaspoon of cinnamon until well blended.
Add flour and baking powder whisking until the batter is smooth. Whisk for at least one minute or two ensuring no clumps of flour remain. Let sit.
Place remaining (¾ stick) of butter cut into thin squares in 13x9-inch glass baking dish. Place the dish in the oven until butter melts and starts bubbling, about 5 minutes. Do not burn butter watch carefully at this step. Remove the dish from the oven.
Promptly place the apple slices mixture atop melted butter in the baking dish.
Then quickly whisk the batter again for 15 seconds creating bubbles and pour batter evenly over the apples. When pouring the batter evenly over the apples do not mix it together or spread it around after pouring into the glass dish.
Bake pancake until puffed and brown, about 20 minutes. Sprinkle it with powdered sugar and serve warm.