Preheat oven to 350°F. Place 12 cupcake liners in a muffin tin.
Combine brownie mix, eggs, water and oil in a large bowl and stir to blend. Add mix to the cupcake liners until almost full. Bake for 30 minutes or until a toothpick inserted in the centre of a cupcake comes out clean. Cool completely.
After the cupcakes have cooled, begin to make the peanut butter topping by combining sugar and corn syrup in a small pan on the stove on medium heat. Bring to a boil over medium heat then remove from heat. Mix in peanut butter and stir to combine. Drop peanut butter mixture on top of the cupcakes (about 1 teaspoon each). Set aside to cool.
When the peanut butter topping has cooled, start making the chocolate topping by combing chocolate chips, butter and corn syrup in a small saucepan on the stove. Cook on low heat, stirring constantly, until chocolate has completely melted. Remove from heat. Drop chocolate topping on top of the peanut butter topping (about ½ to 1 teaspoon each). Sprinkle chopped peanuts on top. Let cool.