Line an 8-by-8-inch baking pan with parchment paper.
There are two ways to make the nama chocolates. For a more purely chocolate confection , heat the heavy cream and butter in a saucepan to 120°F. (Take care not to overheat the heavy cream or the chocolate will separate.) Remove from heat. Add the chocolate to a large heatproof bowl and microwave for 15 seconds. Pour the cream into the softened chocolate to temper it. Add the optional liquor or vanilla extract and a pinch of salt. Whisk until creamy and homogeneous. Skip the next step.
If making Matcha variation: For more matcha flavor, heat the heavy cream and butter to 110°F in a saucepan, until the butter has melted. Immediately remove from heat and mix in the white chocolate, vanilla extract, and salt until incorporated and creamy. Sift in the matcha and whisk until homogeneous.
Pour the chocolate mixture into the prepared pan. Even and smooth out the top of the chocolate. Tap the pan against the counter to get rid of air bubbles. Cover with plastic wrap and refrigerate at least 3 hours.
Slice the chocolate into 24–36 equal pieces, depending on how big you want them to be. Dust with either the cocoa or the matcha. Garnish with edible gold flakes or sea salt, if using.
Nama chocolates should be refrigerated in an airtight container and eaten within 5 days.