And I went a little overboard with the undercooking -- I love cookie dough and underdone baked goods in general, so I took this out after about 30 minutes instead of the 35-45 that Heidi suggests. It wasn't enough and the cookie was really kind of soupy (although delicious!)... until I put it in the fridge, still in the skillet overnight. Then the nirvana hit and it was sort of like just-barely-cooked solid dough. You. guys. So. good.
Next time, though, I'll leave it in the oven for another 5 minutes -- I would have been nervous to serve it to anyone when it was that uncooked. (Note that it didn't stop me and Jared from eating the entire thing ourselves over the course of not very many days.)
3 cups whole-wheat flour [I used 2 c whole wheat pastry flour and 1 c AP)
1 1/2 teaspoon baking powder
1 teaspoon baking soda
1 1/4 teaspoon fine grain sea salt
8 ounces / 225 g (2 sticks) cold unsalted butter, cut into 1/2-inch pieces [I used Earth Balance sticks]
1 cup / 5 oz / 140 g dark brown sugar
1 cup / 7 oz / 200 g sugar
2 large eggs
2 teaspoons pure vanilla extract
8 ounces / 225 g bittersweet chocolate, roughly chopped into 1/4- and 1/2-inch pieces [I used Ghiardelli 60% semisweet chips]
Preheat the oven to 350°F / 175°C degree oven, with a rack in the middle. Butter a 10 (25cm) or 11-inch (28cm) ovenproof skillet, one that is at least 2-inches (5 cm) deep. [I sprayed with that Pam flour baking spray.] If you're unsure, measure, because if you use a too small skillet, you'll have a messy overflow.
Sift the dry ingredients into a large bowl.
In another large bowl, or in the bowl of a stand mixer fitted with the paddle attachment, add the butter and the sugars. Mix just until the butter and sugars are blended, about 2 minutes using the mixer on low speed. Use a spatula to scrape down the sides of the bowl along the way. Add the eggs one at a time, mixing until each is combined. Mix in the vanilla. Add the flour mixture to the bowl and blend on low speed until the flour is barely combined, about 30 seconds. Scrape down the sides and bottom of the bowl.
Add most of the chocolate to the batter. Mix just until the chocolate is evenly incorporated. Use a spatula to scrape down the sides and bottom of the bowl, then scrape the batter out into the skillet, pressing it out into an even layer. Sprinkle any remaining chocolate across the top, and casually press it into the dough a bit, just enough that it isn't riding directly on top of the dough.
Bake the cookies for 35-45 minutes, or until until the dough is a deep golden brown along the edge, and the center has set. Remove from oven and let cool a bit before slicing into. Cute into wedges or small squares.
Makes one large skillet cookie, which you can cut into as many cookies as you like.