Preheat oven to 350 degrees F (175 degrees C). Grease an 8x8 inch baking pan.
In a medium saucepan, melt the butter over low heat. Remove from heat and stir in the cocoa and sugar. Add the eggs one at a time, stirring the mixture after each egg.
Stir in the vanilla, flour, and salt. Gradually stir in the Irish cream liqueur. Spread the batter evenly into the prepared pan.
Bake for 25 to 30 minutes, or until a toothpick inserted in the center comes out clean. Let cool.
In a medium saucepan, melt the chocolate chips over low heat. Spread over the cooled brownies.
Let cool before cutting into squares.
Interesting Facts
Irish cream liqueur is a whiskey-based liqueur that originated in Ireland.
Brownies are believed to have been invented in the United States in the late 1800s.
Chocolate chips are a relatively recent invention, first appearing in the 1940s.