Preheat An Oven To 375 Degrees F (190 Degrees C). Spray An 8X8 Inch Baking Dish With Nonstick Cooking Spray. Season Chicken Breasts With Salt And Pepper; Place In Prepared Dish. Combine Orange Marmalade, Horseradish, And Rosemary In A Small Bowl; Pour Over Chicken. Bake The Chicken In The Preheated Oven Until No Longer Pink In The Center, And The Juices Run Clear, 30 To 35 Minutes. An Instant-Read Thermometer Inserted Into The Center Should Read At Least 165 Degrees F (74 Degrees C).