Whisk the dry mix: In a small saucepan off heat, whisk sugar, cocoa powder, espresso powder, and salt until no cocoa lumps remain. This prevents clumping later.

Add liquids: Whisk in 3/4 cup water and the corn syrup until smooth. The mixture will be thick at first, then loosen.

Heat gently: Place the pan over medium heat. Stir continuously as it warms. When it reaches a gentle simmer, reduce heat to low. Avoid a rolling boil, which can scorch cocoa.

Simmer to thicken: Cook 3–5 minutes, stirring often, until glossy and slightly thick. It will thicken more as it cools, so don’t over-reduce.

Finish with vanilla: Remove from heat. Stir in vanilla. Taste and adjust with a pinch more salt or a tablespoon of water if it’s too intense.

Cool and bottle: Let the syrup cool 10–15 minutes. Pour into a clean glass jar or squeeze bottle. For the smoothest texture, strain through a fine mesh sieve first.

Use it: Start with 1–2 tablespoons per 8–12 oz coffee or milk. Add more to taste.