Cut the peach halves into quarters. Arrange them in a 9-inch bundt pan.
Separate the eggs and place the yolks and egg whites in separate bowls. Add sugar to the egg whites and beat until stiff and glossy. Gradually add milk, oil, and vanilla extract while continuing to beat. Sift in the flour and baking powder and mix well.
Add sugar to the egg yolks, then add milk, oil, and vanilla extract. Finally, sift the flour and baking powder into the batter. Mix everything well. You should now have two bowls with two different colored batters.
Pour about half of the white batter into the cake pan over the peaches.
Sift cocoa powder generously over the white batter.
Pour half of the yellow batter into the cake pan and sift cocoa powder generously over the batter.
Repeat with the remaining batter and cocoa powder. The top layer should be yellow batter. Bake for 50 minutes.