In a saucepan, warm the heavy cream and butter on low heat, only to melt the butter.
Slowly add the warm cream mixture to the matcha and whisk or stir until there aren’t any lumps. Set aside.
Rough chop the white chocolate. Melt, either by placing in double boiler with hot water that has been brought to a boil & turned off, or on extremely gentle direct heat in a covered saucepan. If you use direct heat, do not wait until fully melted. Remove when partially melted & stir until fully melted. Return to heat only if absolutely necessary.
Once the chocolate has melted completely, pour in the matcha cream and mix well.
If the chocolate starts to separate or look grainy add in a tablespoon of hot water and the chocolate mixture/ganache will come back together. Add another tablespoon if needed.
If you want square truffles, spoon the ganache into a silicone ice-cube tray. To get a smooth and even surface, scrape off the top of the mold. Put the molds into the fridge for about 4-5 hours to solidify the ganache and then carefully pop the cubes out of the molds.
If you want round truffles, refrigerate the ganache for at least ½ hour. Remove and with two spoons, scoop 1-in balls of the ganache onto a baking sheet. With your hands, roll the balls into smooth, uniform shapes.
Now, you get creative. If you wish to coat in chocolate, do so. If you like simplicity & the stark taste of matcha, sift some matcha on a plate and coat each truffle. You can mix the matcha with some confectioner’s sugar if you wish. Decorate further as you choose (for instance, sprinkle with crushed raspberry powder).