In a large mixing bowl, whisk together the melted butter, granulated sugar, and brown sugar until well combined. Add the egg and vanilla, and whisk until the mixture is smooth and slightly creamy.
In a separate bowl, whisk together the flour, baking soda, salt, and matcha powder.
Fold the dry ingredients into the wet mixture using a spatula or wooden spoon. Mix just until no streaks remain—don’t overmix!
Gently fold in the white chocolate chips until evenly distributed.
Scoop the dough using a cookie or ice cream scoop. Place the scoops on a tray or plate and chill in the fridge for at least 1–2 hours (or overnight). Don’t skip this—it helps the flavors develop and prevents spreading!
Preheat your oven to 180°C (350°F). Roll chilled dough balls slightly and place them on a parchment-lined baking sheet, 2-3 inches apart.
Bake for 11–14 minutes, or until the edges are set and the centers look slightly underbaked. They’ll continue to cook as they cool!
Let the cookies cool on the tray for 5 minutes before transferring to a wire rack. Enjoy warm or store in an airtight container for up to 4 days.