Heat oven to 500 degrees.
Heat butter in the skillet over medium-high heat until sizzling. Add apples, brown sugar, and cinnamon; cook, stirring frequently with heatproof rubber spatula, until apples are golden brown, about 10 minutes. Off heat, stir in lemon juice.
While the apples are cooking combine the pancake mix, rice milk and vanilla extract. Mix until no lumps remains; set aside.
Pour the batter around the edges of the pan, then over the apples. Place skillet in oven and immediately reduce oven temperature to 425 degrees; bake until pancake is set and the top is a light golden brown, about 15 to 18 minutes. (18 to 20 minutes if using a 10 inch skillet)
Remove hot skillet from oven and loosen pancake edges with heatproof rubber spatula. Place a plate on top of the skillet and invert the pancake onto the plate. Dust with powdered sugar, cut into wedges, and serve.