1/2 cup (100 grams) granulated natural cane sugar
2 tablespoons (14 grams) dark cocoa powder (I use Valrhona)
1/2 teaspoon vanilla extract
Add the sugar along with 1/2 cup (125 ml) of water to a 2-quart (2.2 L) pot. Bring to a boil, and cook for 2 minutes until the sugar has completely dissolved, slightly thickened, and syrupy. Reduce the heat to low.
Whisk in the cocoa powder and vanilla extract until the cocoa is completely dissolved. Cook for 1 minute more. The syrup will be thin and liquidy. Transfer to a glass jar and set on the counter to cool completely. Store, tightly sealed, in the fridge for up to 3 months. Shake well before each use.