In a small saucepan, combine the whole milk, 2% milk, sweetened condensed milk, cacao powder, instant espresso, and salt.
Bring to medium-high heat and whisk constantly until smooth, fully combined, and just starting to steam (about 3–5 minutes).
Remove from heat and stir in the vanilla and peppermint extracts.
Pour into a heatproof mug and top with your desired toppings.