Preheat oven to 400F°.
Cream butter and brown sugar until fluffy, about 3 minutes.
In another bowl, combine 1 3/4 cup flour, oats, cinnamon, salt, and baking soda; stir into the creamed mixture until well blended.
Set 2 cups of this mixture aside and press the remainder into a greased and/or lined 9×13 pan.
Core, peel, and dice apples into thin, bite-sized pieces. Toss them with juice and 3 Tbsp flour. Spread the apples over the dough base. Sprinkle cinnamon chips on top of apples.
Heat dulce de leche in microwave for 30 seconds. Repeat as needed until it becomes pourable, then drizzle it over the apples. Spread with a spatula if necessary. Sprinkle the reserved flour and oat mixture over the top and press down gently. Bake for 25-30 minutes, until set and golden.
Remove from the oven and allow to cool. Cut into small bars and refrigerate until ready to serve or serve immediately while still warm. Store in an airtight container in the fridge for up to 3 days.