Step 1
Preheat the oven to 375 degrees F (190 degrees C). Line a 9x13-inch baking pan with nonstick aluminum foil.
Step 2
Whisk flour cocoa powder and salt together in a medium-sized bowl until evenly combined. Set aside.
Step 3
Fill the bottom of a double boiler halfway with water and bring to a simmer about 5 minutes; reduce heat to lowest setting. Add white chocolate chips bittersweet chocolate and butter to the top of the double boiler and heat stirring constantly until melted about 5 minutes. Remove from heat.
Step 4
Beat eggs and sugar together in a large mixing bowl using an electric mixer until light and fluffy about 3 minutes. Add melted chocolate mixture beating until combined. Beat in flour mixture. Whisk stout beer in to create a thin batter. Drop semi-sweet chocolate chips evenly on top allowing some to sink in.
Step 5
Pour batter into the prepared pan.
Step 6
Bake on the center rack of the preheated oven until a toothpick inserted in the center comes out almost clean 30 to 40 minutes.
Step 7
Allow brownies to cool for 1 hour at room temperature.
Step 8
Pour Irish cream liqueur into a small saucepan and heat until simmering about 3 minutes; do not boil. Place dark chocolate chips in a bowl and pour heated Irish cream liqueur on top. Stir until evenly melted. Allow ganache to cool and thicken about 10 minutes.
Step 9
Pour ganache over the cooled brownies and spread evenly over the top. Refrigerate brownies until ganache is set at least 1 hour.