1. Preheat oven to 350 degrees Fahrenheit. Prepare nine three-and-a-half-inch mini cast-iron skillets (see tip) by placing them on a cookie sheet.
2. In a large bowl, mix brownie mix, eggs, oil, brown sugar, and vanilla extract. Add chocolate chips and mix well.
3. Divide batter into skillets, filling until they are three-fourths full. Bake for 20 to 25 minutes. Do not overbake! Top with a scoop of ice cream, if desired.
If you don’t have mini skillets, make these into delicious brownie cookies instead. Drop heaping spoonfuls of batter onto a parchment-lined cookie sheet. Bake at 350 degrees Fahrenheit for 12 minutes, then let cool for two minutes. Serve warm with ice cream. Yields approximately 20 cookies.