Put an 8x8 glass dish* in the center of the oven and preheat 450 degrees.
1 thinly sliced apple (any kind, a mandolin makes easy work of this)
2 Tablespoons butter
In a skillet, sauté apples and butter over medium heat for 3-5 minutes.
While the apples are cooking, blend the following:
4 eggs**
1/2 cup flour
1/2 cup milk
3/4 teaspoon salt
3 Tablespoons sugar
1 teaspoon vanilla
2 Tablespoons melted butter
Remove the 8x8 glass dish from the oven. Pour in apple mixture. Stir letting the butter coat the pan, then distribute apples evenly. Pour the egg mixture over the top. Using oven mitts (remember the dish is hot!), place the dish into center of the oven and cook for 15 minutes. The Dutch Baby will come out puffy, then slump. Let cool a few minutes before serving.***
*If you have an appropriate sized cast iron skillet, you can just use that to sauté the apples, then pour the egg mixture over the apples and put the cast iron skillet directly in the oven.
**If you only have 3 eggs, make it anyway. It's still good.
***I think this is delicious as is. If it is not sweet enough for you, sprinkle with powdered sugar (this makes for a beautiful presentation as well), and add syrup if desired.