Preheat oven to 350 degrees. Line cookie sheets with parchment paper, set aside.
In the bowl of a stand mixer, combine sugars and butter, beat until fluffy (about 2 minutes). Add vanilla and one egg, mix until just combined, then add the second egg, mixing until incorporated.
In a medium size mixing bowl, whisk together flour, baking soda, baking powder, corn starch and salt. With mixing speed on low, gradually add dry ingredients mixing until no “flour” pockets remain.
Remove bowl from stand and fold in chocolate chunks. You’ll want to add all of the shards or shavings that result when chopping bars- that’s what makes these “freckled!” Place dough into the refrigerator to chill for 1 hour. Remove and let stand for 5 minutes before scooping and placing onto the prepared sheets.
Place in oven and bake for 10-12 minutes- the edges will become light brown and the centers should still look slightly soft and gooey- they’ll firm up once they’ve cooled for a bit. Remove from oven and allow to cool on sheets for 3 minutes, then transfer to a wire rack to cool completely.