For the Pancake:
1/2 Cup all-purpose flour
1/2 Cup milk
1 Tablespoon sour cream
1/2 teaspoon salt
1 teaspoon grated lemon zest
1 teaspoon Vanilla extract
Preheat oven to 400.
To make the apple filling, in a 10 inch ovenproof frying pan over medium heat, melt the butter. Add the apples, sugar and cinnamon and saute', stirring constantly, until the apples begin to soften and brown lightly, 3-5 minutes. Remove from the heat.
To make the pancake, in a bowl, using an electric mixer set on medium speed, beat the eggs until lightly frothy. Add the flour, milk, sour cream, salt, vanilla and lemon zest and beat just until a smooth batter forms.
Immediately pour the batter over the apples in the hot pan and place in the oven. Bake until nicely puffed and golden brown, about 25 minutes.
Using a small fine-mesh sieve, lightly dust confectioners' sugar over the top. Serve this directly from the pan, cut in half or into wedges.