Preheat oven to 325 degrees and line parchment paper on baking sheet.
In a large mixing bowl, sift the flour, matcha powder, and baking powder, and mix together. In another bowl, combine the brown sugar, granulated sugar, egg and butter together using a whisk until creamy.
Mix the dry ingredient into the wet ingredient until the cookie dough is all blended. When everything is all mixed together, add the white chocolate chip into the mixture.
Drop dough by rounded tablespoons onto baking sheet, making sure they are 2-3 inch apart. Bake the cookies for 10-12 minutes, or until edges are lightly browned. Cool cookies for about 5 minutes and transfer to a rack to cool completely.