Prepare the cold brew coffee.
Add all the sugar, water, and rosemary to a saucepan and bring to a boil.
Then, simmer for about a minute and a half.
Let it cool to room temperature.
Mix the cold brew, syrup, milk, and ice in a cocktail shaker.
Pour over a glass with a large ice cube.
Add Bom Bom Nilli Vanilli and enjoy!