Melt butter in a med/large saucepan over med/high heat.
Core apples (you can leave the skin on for a more rustic applesauce) and roughly chop them.
Divide the oatmeal into four bowls. Top with applesauce and additional toppings if desired.
Oatmeal can be made several days ahead and stored in an airtight container in the refrigerator. Rewarm with an additional splash of milk over low heat or in the microwave.