Heat oven to 350ºF. Generously grease with shortening and lightly flour 12-cup fluted tube pan. In medium bowl, beat cake mix, milk, peanut butter, vanilla and eggs with electric mixer at low speed 1 minute, scraping bowl constantly. Beat 2 minutes at medium speed, scraping bowl occasionally. Stir in miniature chocolate chips. Pour into greased and floured pan.
Bake 45 to 55 minutes or until toothpick inserted near center comes out clean and top springs back when touched lightly near center. Cool in pan 10 minutes. Invert onto wire rack or heatproof serving plate; remove pan. Cool completely, about 1 1/2 hours.
In small saucepan, melt all Icing ingredients over low heat, stirring constantly until smooth. Drizzle warm icing over top of cooled cake, allowing some to drip down sides. Sprinkle peanuts over icing.