Mix the Cornstarch Slurry: In a small bowl, combine the cornstarch with 2 tablespoons of milk and whisk until smooth. Set it aside.
Warm the Milk: In a medium saucepan, heat the remaining milk over medium heat until it’s warm but not boiling. Stir occasionally to avoid scalding.
Add Dry Ingredients: Whisk in the cocoa powder, sugar, and a pinch of salt until completely dissolved.
Thicken the Mixture: Stir in the cornstarch slurry and bring the mixture to a gentle simmer, whisking constantly. Cook for 3-4 minutes, allowing it to thicken to a creamy consistency.
Melt the Chocolate: Remove the saucepan from the heat and stir in the finely chopped dark chocolate. Keep stirring until the chocolate is fully melted and the hot chocolate is smooth and glossy.
Serve and Enjoy: Pour the thick Italian hot chocolate into mugs. Top with whipped cream, chocolate shavings, or a sprinkle of cinnamon, and serve immediately.