Beat the eggs, sugar and baking powder to high speed until fluffy.

Reduce speed and add in the oil and milk and continue beating for about a minute.

Add in the flour and mix in.

In a separate bowl take a cup of batter and add in the cocoa powder and mix in well.

In a greased baking tin, pour in a portion of the plain batter and tap the baking tin so the batter sits in evenly. Then add in the cocoa powder batter and finish with the plain batter. Tap the baking tin so the batter sets in evenly.

Now take a butter knife and gently cut through the batter to mix in the batters.

Bake the cake in a 350° oven for 30 to 40 minutes.

Once cooked, let it cool before cutting the cake.