Preheat oven to 350 degrees F. and spray 12 count muffin tin with cooking spray.
Cut each bagel half into 1/2 inch pieces and place into large mixing bowl. Core and slice apple, cut into small pieces.
Melt butter into medium skillet over medium heat. Add apples, brown sugar and cinnamon. Stir and cook for 2 minutes then pour over cut bagels and stir to combine.
Add buttermilk, egg, vanilla and salt to bowl, stir to combine. Spoon bagel mixture into muffin tins about 3/4 full. Sprinkle each with pinches of oatmeal and brown sugar. Bake for 15-17 minutes until set. Remove and let cool for 15 minutes before transferring. Serve room temperature.