Preheat your oven to 350°F (175°C).
In a medium bowl, whisk together the all-purpose flour, baking soda, and kosher salt. Set aside.
In a large mixing bowl, combine the softened salted butter, brown sugar, and sugar. Cream together until light and fluffy, about 2-3 minutes.
Add the egg, egg yolk, and vanilla extract to the butter-sugar mixture. Beat until well combined.
Gradually add the dry ingredient mixture to the wet ingredients. Mix just until combined.
Gently fold in the semi-sweet chocolate chips and chopped maraschino cherries until evenly distributed.
Using a cookie scoop or tablespoon, drop rounded balls of dough onto a lined cookie sheet, leaving about 2 inches of space between each cookie.
Before baking, sprinkle a tiny pinch of flaked salt on top of each dough ball.
Bake the cookies for 10-12 minutes or until the edges are lightly golden.
Let the cookies cool on the cookie sheet for about 5 minutes before transferring them to a cooling rack.