the cake to moisten it? Like you would simple syrup?
Absolutely! I just did this with caramel syrup on a carrot cake because I was too lazy to make a simple syrup. It worked wonderfully!
I am a relatively new "caker" and haven't used this technique. What exactly do you do - brush the flavoring on the cake? Are you doing this instead of adding flavoring to your buttercream or what is the purpose? Do you simply brush it on the layers or do you poke holes in the layers? I am always learning new things! Thanks.
Some people poke holes in the cake, but I don't. I pour about 1/8c. into a dish and brush it on the top of my layers with a pastry brush. Be careful that you don't use too much or the cake will be soggy. The purpose can be to either add more flavor, add another flavor, or to moisten the cake a little.