In a pot, put milk, sugar, salt, cornstarch, and Matcha powder. Heat at medium heat whisking constantly until boiling. Turn down to low heat, and cook further until thickened.

In a medium bowl, whisk an egg and yolks, and slowly add hot milk mixture whisking well. Put back to the pot, and cook at medium heat until boiling, about 2 minutes. Then strain the mixture with a strainer, add butter, and mix well.

Divide into 4 dishes, and refrigerate for a couple of hours.

Top with whipped cream, and sprinkle a little bit of Matcha powder for garnish.