Use a funnel to pour the simple syrup into a plastic squeeze bottle with a pour spout.
For Bigger Cakes (6" or larger):
Poke holes into the top of the cake with a bamboo skewer.
Brush the top of the cake with the syrup using a pastry brush (this will allow the cake to be moistened on the outside).
Pour the syrup over the cake so that it seeps into the holes and let it sit for 2 hours so it absorbs completely. This will make the inside of the cake moist.
For Small Cakes (less than 6"):
You can follow the same steps as with big cakes but you can cut the cake in half first. This way you can moisten the bottom half more efficiently. Poke holes into both sides of the cake.
Brush syrup on both sides of the cake using the pastry brush. The smaller cakes only need about 30 minutes to soak. Place the halves back together.
The cake is now ready to frost as desired and serve.
Notes
The amount of syrup you will use depends on factors such as how dry the cake is, how moist you would like it, sweetness of the cake, the size of the cake, the density of the cake (cakes that are more spongy will absorb more syrup) etc. Adjust it according to your personal preference.
For a 9″ cake that is 2″ high, I used about ½ cup of simple syrup.
Work over a baking sheet and rack so that you don't make a big mess.
It's better to use a silicone brush rather than a brush with pig hair bristles as I find the hairs sometimes fall out and get into the food.
For an alternative to simple syrup, professional bakers also use milk to soak the cake.
If you're unsatisfied with the moisture of your cake, you could also turn it into cake pops by combining it with frosting.
Adding frosting between the layers and on the outside of the cake also helps with the end result.
The nutrition information is for the simple syrup only. It gives you an idea as to how many calories you are adding by soaking the cake with ½ cup syrup.