Hi,
Steve Katz reverse engineered Walker Brother's apple pancake. It was featured in the Tribune's food section during January, 2007.
His recipe was calculated to up the protein in the batter using skim milk, additional gluten and egg whites. The pancake is a variant of a popover. He also replicated their two-stage cooking by setting the mixture at a low temperate. Then moving to a much hotter oven, which caused the batter to inflate.
Regards,