This recipe is from an IC safe cookbook.
1/3 cup brown sugar (not packed)
1 tsp ground cinnamon (if can tolerate)
2/3 cup white sugar
1/2 cup butter, softened
1 1/2 tsp vanilla extract
1 1/2 cups all-purpose flour
1 3/4 tsp baking powder
1/2 cup milk
1 apple, peeled and chopped (use the lower acid Gala or Fuji apples)
Preheat oven to 350F. Grease and flour 9" x 5" loaf pan. Mix brown sugar and cinnamon together in a bowl and set aside. Beat white sugar and butter together in a bowl using an electric mixer until smooth and creamy. Beat in eggs, one at a time, until incorporated. Add vanilla extract. Combine flour and baking powder together in another bowl. Stir into creamed butter mixture. Mix milk into batter until smooth. Pour half the batter into the prepared loaf pan. Add half the apples and half the brown sugar cinnamon mixture. Lightly pat apple mixture into batter. Pour the remaining batter over apple layer; top with remaining apples and add more brown sugar/cinnamon mixture. Lightly pat apples into batter. Swirl brown sugar mixture through apples using a finger or spoon. Bake in the preheated oven until a toothpick inserted in the center of the loaf comes out clean, 30 to 40 minutes.