Prepare your cake
Step 1 To replicate the inside of a real watermelon , we ’ re going to colour your cake batter ! Add a few drops of hot pink or red Colour Mill dye to your batter and mix on low speed until fully incorporated .
Step 2
Pour 1 / 4 of the batter into a 6-inch hemisphere pan and a 6-inch round pan - this round pan will be the base layer for your watermelon cake .
Step 3 Fold your chocolate chips into the remaining batter - these will be your watermelon ‘ seeds ’. Fill the pans with the remaining batter until they are 3 / 4 full . Bake according to your recipe ' s instructions and let the cakes cool completely . Once cooled , refrigerate them overnight to chill . Distributing the batter this way will make sure the chocolate chips are more evenly distributed ( we don ’ t want them all sinking to the bottom !).
Step 4 Using a cake leveler , trim off any bulging or uneven parts of your cakes to create a flat surface . For the hemisphere cake , cut it into two even layers . To maintain the dome shape when adding ganache , trim an extra 5mm off the bottom larger layer . This extra trimming accounts for the thickness of the ganache and helps preserve the rounded shape of the dome . For the 6-inch round cake base , evenly cut this to size to match the height of your hemisphere layers .