Step 1In the bowl of a stand mixer, beat the butter and both sugars until light and fluffy, 3 to 5 minutes.
Step 2Meanwhile, in a separate bowl whisk together the flours, baking soda and powder, ¾ teaspoon salt and caraway seed.
Step 3Add the egg and vanilla to the butter mixture and continue to beat until fully combined. Add the dry ingredients and beat until almost fully incorporated. Add the chopped chocolate and stir to combine. Wrap the dough in plastic wrap and refrigerate for at least 1 hour, and up to 3 days.
Step 4Heat the oven to 350 degrees. Scoop the dough (about 2 tablespoons for each cookie) and space the cookies a few inches apart o a parchment-lined baking sheet. Sprinkle each cookie with a little kosher salt. Bake the cookies until they are crisp on the edges but still soft in the middle, about 15 minutes, rotating halfway through for even baking.