Grease and flour or line your cake tin. Read recipe notes for what tins I recommend you use for this recipe.
Preheat the oven to 175°C or 350°F.
Place the butter and cream in a bowl and melt in a pan over low-medium heat, or place in the microwave in 30-second intervals until the butter has melted. Add the vanilla extract and additional flavourings (if using)
Mix together the flour, cornstarch, baking powder, and salt in a large bowl and set aside.
Whisk the eggs and sugar in a medium-sized bowl for 5-7 minutes until very light, fluffy, and off-white.
Add about 1/3 of the dry ingredients into the egg mixture and carefully fold it in using a spatula. Add 1/3 of the butter and cream mixture and fold that in. Repeat the process until all ingredients have been added, careful not to mix too much air out of the batter.
Once all the ingredients have been incorporated, pour the batter into the prepared tin(s) and bake for 25-30 minutes. Allow to cool completely and store in an air-tight container at room temperature for 3-4 days, or 4-5 days in the fridge.