So what do you do with that leftover fancy cocoa powder you bought to make that delicious, Nutella-esque chocolate and peanut concoction? You make your own cocoa mix! And trust me, this is waaaaaaaay tastier than that stuff you buy at the grocery store.

Ingredients
1/2 cup (100 grams) granulated sugar
1 tablespoon (8 grams) cornstarch
3 ounces (85 grams) bittersweet chocolate, roughly chopped
1/2 cup (40 grams) Valrhona cocoa powder
1/4 teaspoon vanilla extract
1/8 teaspoon fine sea salt

Combine all ingredients in a food processor and blend until thoroughly pulverized.

Before pulverization:

After pulverization:

To use (stovetop version): Heat one cup of milk in a saucepan over medium heat until it begins to steam. Add 3 tablespoons cocoa mix. Whisk over heat for another minute or two, until it begins to simmer and mix is completely dissolved. (Obviously you can make more than one cup at a time, depending on how many people you're serving.)

To use (microwave version): This mixes together better if you heat the cocoa mix with the milk rather than mixing it after the milk has been heated. Measure 3 tablespoons cocoa mix into one cup of milk but don't bother stirring it. Heat for 90 seconds and then stir vigorously. Then heat for 20 more seconds or until cocoa is at desired temperature. (Aside: my microwave is pretty wimpy, so you may want to reduce these times if you are using a more powerful model.)

Bonus tip--I store my cocoa mix in a container with the measurements noted on it to make life easy:

Recipe source: Smitten Kitchen