Preheat oven to 200 °C for 10 minutes. Grease a 6 inch round tin or 8½ inch loaf tin, and line the bottom.
Beat the sugar and yogurt for 5 minutes on high speed. Add baking powder and baking soda, beat in on low, and allow to stand for 3 minutes. You will find that bubbles appear.
Beat in the melted butter and vanilla essence. Next, slowly add the flour in 4 lots, blending in well after each addition.
Take ⅓ of the dough in a separate bowl and stir in the cocoa. {You can make just vanilla as well, in which case, omit this step}
Add ½ the vanilla batter to the bottom of the tin, smooth it out to spread across the whole surface. Add all the chocolate batter, and smooth it out too. It might be pretty thick, as mine was. Top with the remaining vanilla batter to make a third layer. Top with glazed cherries if using.
Bake at 200 °C for 10 minutes, reduce temperature to 170 °C and bake for 40-45 minutes or till a toothpick inserted into the cake comes out clean.
Cool the cake for 30 minutes and then overturn onto a plate.
Wait for at least 2 hours before slicing it, else it doesn't slice neatly.