Preheat the oven to 350 degrees F. Spray a 9x9-inch pan with nonstick spray, line with parchment paper and spray the paper too.
PREPARE THE BROWNIES:
In a medium bowl, whisk together the flour, salt and baking powder; set aside.
In a large microwave-safe bowl, add the chocolate chips and the butter. Microwave in bursts of 30 seconds until the butter is melted and the chocolate begins to melt too. Whisk the chocolate into the butter until nice and smooth. Let it cool down for a few minutes.
Use an electric hand mixer to add the sugar, Irish Cream and eggs to the chocolate mixture and beat until mixed well. Add the dry ingredients, and beat just until combined.
Scrape the brownie batter into the prepared pan. Bake for 40 minutes, or until the top cracks slightly and a toothpick instead into the center comes out slightly gooey on the bottom of a toothpick. Remove the brownies from the oven and immediately brush the warm brownies with more Irish Cream. Let the brownies cool.
PREPARE THE FROSTING:
Place the butter in a saucepan and heat until melted. Remove from heat and add the Irish Cream and whipping cream. Whisk in the powdered sugar. Pour the frosting on top of the brownies and quickly spread the frosting evenly to the edges to cover the brownies completely. Refrigerate until set. Chilled brownies are easiest to cut. Store brownies in a covered container. They're best if eaten within a couple of days.