Slice Golden Delicious apples into about 1/2’ slices. Lay slices in the bottom of an oval baking dish in two layers—lightly sprinkle brown sugar and cinnamon on top of each layer.
Mix together oats, flour, brown sugar, cinnamon, cardamom, salt, and melted butter; spread evenly over apples.
Cover with foil and bake at 350 degrees for 30 minutes, then bake for 20 more minutes, uncovered. Serve warm with whipped cream or vanilla ice cream.