Be sure to read the post above for more specifics about this easy ganache or see my chocolate chip comparison post! The short answer is no, because we're using milk & butter instead of heavy cream, these will not completely harden at room temperature so you'll want to store them in the fridge if you want the frosting to stay looking nice. If you want the frosting to stay "hard" at room temperature, you will need to use heavy cream. To make a firm ganache, follow the instructions below but use 1/2 cup heavy cream and 1.5 cups chocolate chips (no butter). I personally like the taste of the milk & butter ganache (it's creamier & tastier) but if you need to transport these or stack (between parchment paper), it's best to use a traditional chocolate ganache that uses heavy cream.