Preheat the oven to 350ºF.

Thoroughly grease the inside of four clean canning jars with butter. Set aside.

Prepare the brownie batter per your recipe’s instructions.

Pour the batter into each of the greased jars, filling them one-fourth full. Tap the jars lightly on the counter to release any air bubbles. Place the filled jars on a cookie sheet, arranged so that they are not touching each other.

Bake the jars for 40 to 45 minutes, or until a toothpick inserted comes out clean.

Top with a scoop of vanilla ice cream.