Gently heat the dairy base: In a medium saucepan over a low flame, combine the whole milk and double cream. Stir occasionally until small bubbles begin to form around the edge of the pan and a fine steam rises from the surface — you want it hot but not boiling, around 75°C.

Whisk in the dry ingredients: Add the sifted cocoa powder, caster sugar, and pinch of sea salt. Whisk vigorously for about 30 seconds until the cocoa has fully dissolved, leaving no dry patches on the surface. The mixture will turn a uniform, deep brown colour and smell intensely of chocolate.

Incorporate the chocolate: Remove the pan from the heat and add both the finely chopped dark and milk chocolate. Let it sit undisturbed for 30 seconds to allow the residual heat to begin melting, then whisk gently in a figure-eight motion until the mixture is completely smooth and glossy, with a thick, ribbon-like texture that falls from the whisk.

Add the vanilla: Stir through the vanilla bean paste until evenly distributed. The aroma will shift from pure cocoa to a warmer, sweeter fragrance.

Finish with a frothy top: Return the pan to a very low heat and whisk vigorously for 20 seconds to create a light foam on the surface. The sound will change from a gentle simmer to a rhythmic slosh as air is incorporated.

Prepare for serving: Pour the hot chocolate through a fine-mesh sieve into warmed cups or heatproof glasses to catch any tiny unmelted chocolate bits — this guarantees a flawlessly smooth drink.

Add the theatrical garnish: Top with a generous dollop of whipped cream, a shower of chocolate shavings, a light dusting of cocoa powder, and a cinnamon stick for stirring. The contrast of dark chocolate against white cream is visually striking.