In a large mixing bowl, mix together flour, cocoa, baking soda and salt.
Place chocolate chips and butter in a medium glass bowl. Heat in microwave until melted, in 3- 30 second intervals, stirring each time to check consistency. Do not overcook.
Add sugar, eggs, irish cream and vanilla to chocolate mixture. Whisk together. Microwave on high for 30 seconds, stir and heat again for another 30 seconds until sugar has dissolved and mixture is smooth.
Slowly add dry ingredients to chocolate, stirring to incorporate.
Spray a 9" square baking pan with cooking spray. Spread batter into pan and smooth evenly.
Bake for 20 minutes. Let cool completely.
Slice brownies into squares, and top with a generous scoop of mint chocolate chip ice cream. Add hot fudge topping. Serve immediately.