Heat oven to 350°F; line sheets with parchment.
Beat softened butter and powdered sugar in large bowl 2-3 minutes until smooth and creamy.
Mix in yolk and vanilla thoroughly.
Separately sift flour, matcha, and salt to remove lumps.
Gradually mix dry into wet on low to form dough.
Gently fold in white chocolate chips.
Roll into 1-inch balls; place about 2 inches apart on sheets.
Bake 9-11 minutes until bottoms start turning golden; tops remain pale green.
Cool on sheet 5 minutes; transfer to rack.
Once completely cool, lightly dust with powdered sugar.