Apple Oven Pancake

4 Tbs. (1/2 stick) unsalted butter 

4 cups diced peeled tart apples, such as Granny Smith 

2 Tbs. firmly packed light brown sugar 

Juice of 1/2 lemon 

1/2 tsp. ground cinnamon 

4 eggs, lightly beaten 

1 cup milk 

1 cup all-purpose flour 

1 tsp. vanilla extract 

1/8 tsp. salt 

 Confectioners’ sugar for dusting