Hot chocolate mix

My younger son has been asking for hot chocolate lately.  I've been mixing cocoa powder with a little sugar and some warm milk (to make sort of a roux), then adding more warm milk, but this sounds a little easier.

From the Smitten Kitchen:

Decadent Hot Chocolate Mix
Adapted a little from Cook’s Illustrated

Yield: Just under 1 3/4 cups mix, enough for 9 cups

1/2 cup (100 grams) granulated sugar
1 tablespoon (8 grams) cornstarch
3 ounces (85 grams) semi-sweet chocolate
1/2 cup (40 grams) cocoa powder
1/4 teaspoon vanilla extract
1/4 teaspoon kosher salt

Combine all ingredients in a food processor and blend until powdery. Keeps at room temperature for up to 2 months.

To use: Heat one cup of milk. Add 3 tablespoons hot cocoa mix. Whisk over heat for another minute or two, until it begins to simmer and mix is completely dissolved. 

Other flavor ideas: 

Mexican Hot Chocolate (with some chile powder, cayenne and cinnamon)

Mint Hot Chocolate (with mint extract instead of vanilla; could also use mint chocolate chips)

Mocha Hot Chocolate (with a couple tablespoons of espresso powder)