Mint sugar.
Pick a handful or two of mint leaves- it's not exact, but the more you put in the more flavorful it will be. Wash and dry.
Put in a blender/puree machine with a cup of sugar until it's well mixed and chopped.
Let it sit for an hour or so, so the sugar can absorb the flavor.
Let it dry for a while- at least overnight- spread out. It you want to be sure the moisture is all out leave it out longer, put it in the oven on warm for a while, or put a desiccant packet in whatever container you store it in.
Enjoy.
You can store it in whatever- mason jar, ziplock bag, etc.
It's even yummy if you just eat it by itself.