Heat oven to 350°F. Grease bottoms only of 2 (8×4-inch) loaf pans with cooking spray or shortening.
In large bowl, stir together apples, 1 cup brown sugar, the buttermilk, oil and eggs. Stir in remaining bread ingredients just until dry ingredients are moistened. Pour into pans.
Bake 45 to 55 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes on cooling rack. Loosen sides of loaves from pans; remove from pans and place top sides up on cooling rack. Cool completely, about 1 hour.
In 1-quart saucepan, melt butter over medium heat. Stir in 1/4 cup brown sugar. Heat to boiling, stirring constantly; reduce heat to low. Boil and stir 2 minutes. Stir in milk. Heat to boiling; remove from heat. Cool to lukewarm, about 30 minutes.
Gradually stir powdered sugar into glaze mixture. Place saucepan of glaze in bowl of cold water. Beat with spoon until smooth and thin enough to drizzle. If glaze becomes too stiff, stir in additional milk, 1/2 teaspoon at a time, or heat over low heat, stirring constantly. Drizzle glaze over loaves. Wrap tightly and store at room temperature up to 4 days, or refrigerate up to 10 days.