In a large bowl, combine the flour, baking powder, sugar, cocoa, salt and baking soda. Add the butter and beat with an electric mixer until light and fluffy. Gradually add the milk, beating well after each addition. Pour the dry ingredients into the wet ingredients and mix until just combined. Fold in the chocolate chips. Spoon the batter into greased and floured muffin tins. Bake for 20 to 25 minutes or until toothpick inserted in center comes out clean. Cool in pan on wire rack. Frost with white chocolate frosting.