In a small saucepan, heat the heavy cream on medium-high heat. As it begins to simmer, whisk in the malt powder until well combined. Once the cream has just come to a boil, remove from heat and pour over the chocolate. With a heat proof spatula, stir until all the chocolate has melted and the mixture, also known as ganache, is combined.
Allow the ganache to cool slightly, then cover the bowl with a towel and allow it to chill for several hours or overnight.
Whisk together the cocoa and malt powder for the topping.
Use a tablespoon to scoop out some chocolate and quickly roll it into a ball. Toss in the topping and set aside. Repeat until all of the chocolate has been used.
The truffles will soften as they warm up so keep them refrigerated prior to serving.