Preheat oven to 350ºF. Prep a 10-inch ovenproof skillet or baking pan (grease if desired.)
In a large saucepan, melt butter, then set aside to cool for 5 minutes. Whisk in eggs, egg yolk and vanilla, then add the brownie mix and baking powder, whisking until thoroughly combined. Stir in 1 cup of chocolate chips. Pour batter into prepared pan. Drizzle 1/4 cup caramel sauce on top of batter, sprinkle with 2 tablespoons of chocolate chips. Bake at 350°F for 18 to 20 minutes. Allow to cool for 15 minutes, and then serve warm with vanilla ice cream and additional caramel sauce drizzled over the top if desired.
Leftover brownie can be kept in an airtight container for up to four days.