Preheat oven to 375 F. Combine flour, sugars, and salt in a bowl. Cut in margarine with a pastry blender or 2 knives until mixture resembles coarse meal. Add peanut brittle, stirring to combine. Arrange apples in a 9 inch baking dish.
Spoon marmalade over apples.
Sprinkle flour mixture over marmalade. Bake at 375 F for 40 minutes. Top each with cup frozen yogurt. Recipe from Cooking Light The Magazine of Food and Fitness Southern Living, Inc.- October 1998, page 121.