Preheat oven to 350°F. Grease and line a 9x5 loaf pan with parchment paper.
Stir cinnamon swirl ingredients into a paste. Set aside.
Whisk eggs and both sugars 1 minute. Add oil, sour cream, and vanilla. Whisk smooth.
Fold in flour, leaveners, salt, cinnamon, and nutmeg until just combined. Fold in diced apple.
Pour half batter into pan. Spread cinnamon swirl over the top. Add remaining batter and swirl gently with a knife.
Bake 55 to 65 minutes until a toothpick shows moist crumbs. Cool 15 minutes in pan then on a rack before slicing.