This is a layered drink. Add 10 or so mint leaves to bottom of Collins glass. Lightly bruise mint, but don’t shred them. Add 0.5 Simple Syrup. Pull mint-syrup up with a bar spoon so it coats the sides of glass, then push back down to bottom. Add 0.5 Lime Juice. Add 3 Demerara Rum. Add crushed ice until glass is ¾ full. Add 4-6 dashes Angostura to top. Swizzle with a bar spoon until glass is frosty, trying to keep all three colors separate. Add more crushed ice on top so that it overflows a bit. Mint garnish.