Preheat oven to 350 degrees F.
Line a cupcake pan with cupcake liners
In a medium mixing bowl combine brownie with ¼ cup water, ¼ cup vegetable oil, and egg until just blended
Put one oreo into each cupcake liner
Top each cookie with 1 teaspoon peanut butter, Nutella or individual soft caramels
Carefully add brownie batter to top of liner
Bake for 20-25 minutes, checking for doneness after 15 minutes. The sides will be firm to the touch when done, however the top will remain soft due to the peanut butter filling
Cool 3-4 minutes in pan, transfer to a serving plate, allow to cool completely
Store in airtight container