Make a simple syrup by boiling the sugar, water, and mint sprigs until sugar is dissolved and it begins to boil. Pour out one cup of bourbon to make room for syrup. Strain Mint sprigs out of syrup and pour into bottle of Bourbon. Mix the contents and put in the deep freeze until it thickens. Serve on the rocks and enjoy.
You can take a couple extra sprigs of mint and put them in the bottle. Also, it's not necessary to use a high quality Bourbon for this to work, Evan Williams works just fine.