01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
03 - In a large bowl, cream the butter, granulated sugar, and brown sugar until light and fluffy, about 2-3 minutes.
04 - Add eggs one at a time, beating well after each addition.
05 - Mix in the milk, vanilla extract, white vinegar, and green food coloring until fully combined.
06 - Gradually add the dry ingredients to the wet mixture, mixing until just combined. Do not overmix.
07 - Using a cookie scoop or tablespoon, drop dough onto prepared baking sheets, spacing about 2 inches apart.
08 - Bake for 10-12 minutes, or until the edges are set but centers are still soft.
09 - Allow cookies to cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.
10 - Melt the white chocolate with oil if using in a microwave-safe bowl in 20-second bursts, stirring until smooth.
11 - Drizzle the melted white chocolate over the cooled cookies using a fork or piping bag. Allow to set before serving.