1Heat oven to 350°F. Grease 10-inch angel food (tube) cake pan with shortening; lightly flour. Measure 3 tablespoons beer into small bowl; set aside. In 1-quart saucepan, heat remaining beer and chocolate over low heat, stirring occasionally, until chocolate is melted. Pour into large bowl; cool to lukewarm, 20 minutes.
2Add remaining cake ingredients to beer mixture. Beat with electric mixer on low speed 30 seconds, scraping bowl occasionally. Beat on high speed 3 minutes, scraping bowl occasionally. Spread in pan.
3Bake 60 to 70 minutes or until toothpick inserted in center comes out clean. Cool 20 minutes; remove from pan to cooling rack. Cool completely, about 1 hour.
4Meanwhile, in 2-quart saucepan over medium heat, melt 1/4 cup butter. Stir in brown sugar. Heat to boiling, stirring constantly; reduce heat to low. Boil and stir 2 minutes. Stir in 2 tablespoons beer. Heat to boiling; remove from heat. Cool to lukewarm, about 20 minutes. Stir in powdered sugar. Add additional beer, 1 teaspoon at a time until soft and spreadable. Spoon over top of cake, allowing some to run down side of cake. Sprinkle with beer nuts.