Whisk together the dry ingredients, and set aside.

Cream the softened butter and sugars until light and fluffy (about 5 minutes). Scrape the bowl several times to ensure even mixing.
It’s easiest to use a stand mixer for this step, but a handheld mixer will also work.

Add the egg and beat well.
Add the vanilla, and beat well again.

Add the dry ingredients to the creamed butter mixture and mix gently until just combined. A little visible flour is okay, because you’ll need to mix in the chocolate.

Add the chocolate and stir gently until it is well distributed through the dough.

Transfer dough to a bowl and press a layer of plastic wrap onto the top of the dough. Then, cover the top of the bowl with a second sheet of plastic wrap.
Refrigerate for at least 24 hours, and up to 72 hours.

Preheat the oven to 350°F.

Notes:

🍪 If you want your cookies to have a more cake-like texture, replace the egg with two egg yolks.

🍪 Don’t have cake flour or bread flour? All purpose flour will work, but the texture may not be as chewy.

🍪 Like nuts? Throw ‘em in! Pecans or walnuts work great. Start with half a cup and work up from there.

Notes:

🍪 The dough can be wrapped tightly in plastic wrap and frozen for up to 3 months.

🍪 Like bigger cookies? Use 3.5 ounces (99 grams) of dough and bake them longer: about 18 to 20 minutes.

🍪 This recipe has a LOT of chocolate, which makes them quite rich. The next time I make them, I will try decreasing the amount of chocolate by just a little. Full disclosure: my husband does not agree with this decision. 🤣

Notes:

🍪. When I baked these, I used a mixture of a 60% cacao chocolate bar (chopped) plus dark chocolate chips plus mini semisweet chocolate chips. The different shapes, sizes, and sweetness of chocolate yielded a great cookie!