I made a batch of cookies to bring to Thanksgiving, and they came out great. The photo, however? Not so much—it just looked like a big blob of brown stuff—so you'll have to take my word for it when I say that they were yummy and well worth making. When have I ever steered you wrong? (Meanwhile, I have got to learn some basic food photography tips.)
The recipe (clipped from the Globe, as I recall) said to use a heaping 2 Tbsp for each cookie, and that would yield "about 19" cookies. When I did that, I got something like 24 and still had some dough left over to add to the skimpier mounds, so I think that it would have to have been closer to an even 3 Tbsp in order to get 19. I don't think it matters all that much, as long as you space them out enough (if they're huge) and keep an eye on them so they don't burn on the edges (if they're not so huge).
Also, the recipe called for 13 oz. of chocolate. The Ghirardelli chocolate I favor comes in 4-oz. bars, so I had to dip into a fourth bar to get the requisite 13 oz. And you know what? I think 12 oz. would have been fine. Really. And you know that I am the high priestess of chocolate, so you can trust me on this. But if you're using a huge block of chocolate (good luck chopping!), by all means whip out the scale and go for 13 oz.
So, here's the recipe, and you'll just have to imagine how scrumptious they looked and tasted. Andy declared them "about as good as you could want from a chocolate-chunk oatmeal cookie."
Chocolate-Chunk Oatmeal Cookies
¾ cup flour
1/8 tsp baking powder
¼ tsp sea salt or kosher salt
11 Tbsp (1 stick + 3 Tbsp) unsalted butter, at room temperature
¾ cup granulated sugar
⅓ cup + 3 Tbsp firmly packed light brown sugar
1 large egg
2 tsp vanilla extract
1⅓ cups quick-cooking (not instant) rolled oats
13 oz. bittersweet chocolate, chopped into small chunks
Heat oven to 325°. Line 2 baking sheets with Silpats or parchment paper.
Sift flour, baking powder, and salt together onto a sheet of waxed paper.
In electric mixer, cream the butter on medium-low speed for 3 minutes. Add the granulated sugar and beat for 2 minutes. Add the brown sugar and beat for 1 minute.
Blend in the egg and vanilla. Blend in the sifted ingredients, the oats, and then the chocolate chunks.
Put heaping 2-Tbsp mounds of dough on the baking sheets, leaving 2½" between them.
Bake for 16–18 minutes or until just set.
Let the cookies stand on the sheets for 2 minutes, then transfer to wire racks to cool completely. Store in an airtight container.