CAKE:
Lightly grease and flour a 25 cm tube or 12-cup Bundt pan.
In a large bowl, cream butter or margarine with peanut butter. Add sugar and combine until light in color. Add eggs one at a time, beating well after each addition. Mixture should be light and fluffy. Add vanilla extract. In a smaller bowl, combine flour, baking powder and salt. Add flour mixture alternately with milk, beginning and ending with flour. Combine batter until it is smooth and creamy. Pour into prepared pan.
Place pan into COLD oven. Set oven to 325^ and bake until the tester comes out clean, about 1 hour 25 minutes. Let cake cool in pan 30 minutes before turning out onto rack. Remove from pan and cool completely. Cover with ganache.
GANACHE:
Heat cream until boiling. Pour over chocolate chips and whisk until it is creamy and smooth. Let cool for 2-3 minutes.
Place cake on a rack and place rack over a large clean baking sheet (to catch the drips). Pour ganache over the top and let it cascade over the cake, enrobing it completely. Remove rack from dirty baking sheet and place it over a clean one. Scrape up remaining ganache and reheat it, if necessary, to pour over cake again if spots are missed.