This is the most important thing to do. It's how you end up with something creamy and beautiful instead of disappointing and gritty and chalky. It's why the hot chocolate in Europe tastes like love and happiness.
Semisweet, bittersweet, or something in between (in terms of % cacao content) will all work. Dark chocolate makes a drink that's less sugary and more intensely chocolaty than if you use milk chocolate. And if you start dark, you can always adjust the balance by adding milk or sugar until it's just right.
5. Use any sweetener you like, but not too much of it.
Real talk: White sugar is not interesting. Try brown sugar, honey, or maple syrupinstead. Maybe Sweet 'n Low, if that's how you roll. You don't need a lot, since this situation is pretty rich already — just a spoonful or two.
6. Heat up the milk and sugar first, then add the chocolate.
You'll melt the chocolate into the milk once it's hot. This way there's no chance of overheating or burning the chocolate by melting it over direct heat; it's the same idea as making a basic chocolate ganache (hot cream + chocolate).
7. You can use cornstarch to make the hot chocolate extra silky-smooth (optional).
This moves things in a slightly more pudding-esque direction. Set aside a little of the cold milk while the rest is heating (about ½ cup) and whisk in the cornstarch (2 to 3 tsp. for 1 quart of milk) until it's smooth.
Add this mixture to the pot full of hot milk after you add the chocolate and whisk, whisk, whisk to make it smooth.
Dissolve 1 Tbsp. instant espresso powder along with the sugar and milk, or justreplace some of the milk with regular brewed coffee. This is actually delicious whether or not you need a pick-me-up; coffee has magical chocolate-flavor-enhancing properties.
PREPARATION 1. Chop chocolate into small pieces. The smaller they are, the faster and more smoothly they will melt. 2. Optional: If using cornstarch, whisk with ½ cup milk and set aside. 3. Heat milk, sugar, and salt in a saucepan over medium-low heat. Stir occasionally. 4. When milk begins to bubble around the edges, stir in chocolate and whisk until smooth. 5. Add cornstarch mixture and any other add-ins. Whisk until smooth and steaming hot. 5. Pour into cups and top with