Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a medium bowl, whisk together the all-purpose flour, baking soda, baking powder, and salt. Set aside.
In a large bowl, using an electric mixer, cream the softened unsalted butter, granulated sugar, and light brown sugar together until light and fluffy, about 3-4 minutes.
Add the egg and pure vanilla extract to the butter and sugar mixture and beat until fully combined.
Gradually add the dry ingredients to the wet ingredients, alternating with the whole milk, beginning and ending with the dry ingredients. Mix until just combined. Do not overmix.
Using a tablespoon or cookie scoop, drop rounded balls of dough onto the prepared baking sheets, spacing them about 2 inches apart.
Bake in the preheated oven for 9-11 minutes, or until the edges are set and just beginning to turn golden but the centers still look slightly soft.
Remove the cookies from the oven and allow them to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.
Store the cooled cookies in an airtight container at room temperature for up to 5 days.