Make a simple syrup with 1/4 cup water and 1/2 cup white sugar. Stir over medium heat until sugar dissolves. Whisk in 1/4 cup unsweetened Double-Dutch Dark Cocoa powder (from King Arthur Flour) and 1/16 tsp kosher salt (half of 1/8 tsp). Reduce heat and simmer for 10 minutes or so, stirring occasionally, until the syrup thickens. Off heat, stir in 1 tsp vanilla extract.
Makes about 1/2 cup. Store sealed in the refrigerator for 1 week.
Add 1 Tablespoon of this syrup to a glass of milk for the best chocolate milk ever.