If using chocolate bars, cut them into small chunks then set aside.
Sift flours, baking soda, baking powder and salt into a bowl. Set aside.
Using a mixer fitted with paddle attachment, cream butter and sugars together until very light, about 5 minutes. Add eggs, one at a time, mixing well after each addition. Stir in the vanilla.
Reduce speed to low, add dry ingredients, and mix until just combined 5 to 10 seconds. Drop chocolate pieces in and incorporate them without breaking them. Press plastic wrap against dough and refrigerate for 24 to 36 hours.
When ready to bake, preheat oven to 350 degrees. Line a baking sheet with parchment paper or a nonstick baking mat. Set aside.
Scoop 6 (3 ½ -ounce) mounds of dough (the size of generous golf balls) onto a baking sheet, making sure to turn horizontally any chocolate pieces that are poking up; it will make for a more attractive cookie.
Sprinkle lightly with sea salt (optional) and bake until golden brown but still soft, 16 to 18 minutes. Transfer the sheet to a wire rack for 10 minutes, then slip the cookies onto another rack to cool a bit more. Repeat with remaining dough, or reserve dough, refrigerated, for baking remaining batches the next day.
Optional: For added indulgence, melt the remaining chocolate bars or chips (10 oz.) and spoon the melted chocolate onto the back of each cookie. Spread with a spatula or butter knife to smooth out the chocolate then place the cookies on a parchment-lined baking sheet and chill until chocolate hardens.
Wrap hardened cookies in plastic and store them at room temperature.
NOTES
To make a cup of cake flour, scoop 1 cup of all-purpose flour into a measuring cup then remove 2 tablespoons of flour and replace it with corn starch.
If you use salted butter instead of unsalted butter you can reduce the amount of salt in the recipe to 1 teaspoon instead of 1 1/2 teaspoons if you prefer.
NUTRITION
Calories: 500kcal
