Line an 8x8-inch baking pan with parchment paper.

Roughly chop the chocolate bars into smaller pieces and transfer them to a large heat-proof mixing bowl.

In a small saucepan, add the cream and butter and bring to a simmer over low heat (about 176°F/80°C). Take it off the heat once it has simmered for 1 to 2 minutes.

Add the heavy cream and butter mixture into the chopped chocolate and stir with a spatula until the chocolate has melted and is well combined.

Pour the melted chocolate into the lined pan. Pop any air bubbles with a toothpick.

Refrigerate for 5-6 hours to set the chocolate or freeze for 2 to 3 hours.

Using a sharp knife cut the chocolate into 1-inch squares. For clean cuts, dip the knife in hot water, then wipe it off with a kitchen towel between cuts.

Dust the sliced chocolates with cocoa powder with a fine-mesh sieve to prevent them from sticking.