Oh man, I love this cake. I don't even bother to frost it...it is really moist and delicious on its own. The recipe is from the Moosewood Book of Desserts, a book I definitely recommend. The pound cake chapter alone is worth the price of the book.
Preheat the oven to 350°F Lightly butter a 10-inch bundt pan and dust it with flour.
In a large bowl, cream the butter and sugar until fluffy. Thoroughly beat in the eggs, vanilla, and orange peel.
In a separate bowl, combine the flour and baking powder. Add the flour mixture by thirds, alternating first with the orange juice and then with the milk, and beat well after each addition. Stir in the nuts and chocolate by hand.
Pour the batter into the prepared pan and bake for 1 1/4 to 1 1/2 hours, until a knife inserted in the center comes out clean.
Cool the cake in the pan for 10 minutes; then turn it out and transfer to a wire rack to cool completely.