Saw something similar on social media this week and recreated it to be gluten free.  Let loaf sit until cold otherwise it is too moist.  I baked this early evening and wrapped when cooled.  This morning it was moist and delicious!

Ingredients:
1 1/2 cup fine rice flour (I use the Asian kind)
1/2 cup tapioca flour/starch
1 tablespoon baking powder
1/2 teaspoon salt
1/2 cup sugar (you could do slightly less)
1 egg, large
1 cup milk
2 teaspoons vanilla extract
2 tablespoon melted butter or oil (I used butter)
1/3 cup sour cream or plain greek yogurt (I used homemade thick yogurt)
1 medium apple – finely diced or coarsely shredded
Cinnamon Mixture – for swirling
1/3 cup sugar
2 teaspoons cinnamon
2 tablespoons melted butter

Method:
Prepare a 8″ L x 4 1/2″W x 3 1/2 H loaf pan . Spray with Pam.
Combine dry ingredients in a mixing bowl.  In another large bowl mix together the egg, milk, vanilla and yogurt or sour cream.
Add the flour mixture to the egg mixture stirring just to combine with a fork.  Put half of batter into prepared loaf pan.  Sprinkle on half the finely diced or coarsely shredded apple.  Place half the cinnamon mixture over apples dropping by teaspoonful.  Swirl with a knife.  Add remaining batter, then remaining apples and cinnamon and swirl again with knife.  Bake for 50 minutes until done.  Test by pricking with toothpick in center.

Let get completely cold before slicing.  Better next day after some moisture is absorbed.