Preheat oven to 400°. In a large bowl, whisk together first 4 ingredients until smooth. Place butter in a 10-in. ovenproof skillet; heat in oven until melted, 2-3 minutes.
Tilt pan to coat bottom and side. Pour batter into hot skillet. Bake until puffed and edge is lightly browned, 16-20 minutes.
Meanwhile, for topping, in a large saucepan, heat butter over medium heat; saute apples until lightly browned. Stir in honey, lemon juice and cardamom. Mix cornstarch and water until smooth; stir into apple mixture. Bring to a boil; cook and stir until thickened, 1-2 minutes. Spoon into pancake; serve immediately.