Marbled Peanut Butter Chocolate Boulders

A dense deeply chocolatey cookie packed with ribbons of mildly sweet peanut butter fudge, or whatever variety of nutty inclusions you prefer. I’ll skip the long saga of how these came to be, since this preamble already contains a lengthy rant about food safety and some pretentious but vital cocoa powder snobbery.

About the Cocoa

The cocoa matters here. There are lots of options, but the most important thing is that the cocoa powder you use is dutch-process or alkalized. The easiest brand to find is Hershey's, but only the "Special Dark" variety is alkalized. Dröste can be found in some grocery stores, and is also alkalized. If you aren't sure if the cocoa you have at home is dutch-process, the packaging usually says. It may also be marked as "dutched," "cocoa processed with alkali," or "european-style." Though that last one is iffy. My dutch-process cocoa of choice is Cacao Barry Extra Brute, if you're overwhelmed by the options — and there are many — grab a bag of Cacao Barry. It'll serve you well, and the 2.2 lb bag of Cacao Barry is cheaper by the ounce than Hershey's.

Internal Temperature and Food Safety

I've always been cautious about recipes that instruct me to bake nearly a third of a pound of raw cookie dough for just a few minutes at 400ºF, as is common in the realm of Levain-like baking online. This never sat right with my understanding of food safety. There's just no way that 7 minutes at that temperature will raise the temperature in the center of the cookie enough to be safe. Turns out, after testing quite a few recipes, I was right. Only one broke 145ºF, one didn't even pass 115ºF (yikes), and the rest stayed between 125ºF and 145ºF. Many of the recipes you'll find online will produce results that could be more dangerous than eating cold raw cookie dough.

The danger zone is a range of temperatures between 40ºF and 140ºF where bacteria can multiply very quickly. Between 60ºF and 120ºF – which one of the tested recipes fell into – their numbers can double in roughly 20 minutes, and double again after another 20 minutes, and so on. Under 40ºF, they mostly stop multiplying. Over 140ºF they stop multiplying and begin to die off. Holding food above 140ºF will kill any bacteria in it, depending on how long you hold it there, and what temperature exactly the food is held at. This takes about 30 minutes at 140ºF, however. Not exactly applicable to cookies. At 145ºF it takes about ten minutes to kill off the bacteria. At 150ºF it takes about three minutes. At 155ºF it takes one minute. At 160ºF it takes 15 seconds. 165ºF is instantaneous.

So, why not just go all the way to 165ºF? Your cookie will be dry. Baking it long enough to get the center to 165 would mean that the outside is much hotter than that, and overbaked. 150ºF is plenty for our purposes, because even after you remove the cookie from the oven and let it rest on the pan the internal temperatures will start to even out. The outside will cool and the center will continue to rise. This trend will slow down as the entire cookie's temperature starts to even out, and then cool down. This process takes longer than the three minutes needed above 150ºF, ensuring our cookies are neither overbaked, nor full of bacteria. Everyone wins.

Ingredients

• 8 oz Unsalted Butter, softened
• 7.5 oz Dark Brown Sugar
• 2 oz White Sugar
• 1 tsp Baking Powder
• 1/2 tsp Baking Soda
• 2 tsp Diamond Crystal Kosher Salt or 1 tsp Table Salt
• 1 large Egg + 1 large Egg Yolk
• 3 oz Quality Dutch-Process Cocoa Powder (see "About the Cocoa" above)
• 6 oz All-Purpose Flour
• 3 oz Cake Flour
• 12 oz Peanut Butter Swirl or any other Peanut Buttery Bits you like - Reese's Pieces, Nutter Butter Pieces, Peanut Butter Chips, Etc.

Directions

1. Preheat oven to 375ºF and line one or two aluminum baking sheets with parchment paper. If planning to bake two pans at once, move oven racks to lower-middle and upper-middle positions. If baking only a single pan at once, move one oven rack to the middle position.
2. In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, brown sugar, white sugar, baking powder, baking soda, and salt until fluffy and light. This should take about 5 minutes on medium-high speed. Scrape down the bowl and paddle as needed to ensure everything is evenly creamed.
3. Add the egg and egg yolk and beat until homogeneous.
4. In a separate bowl whisk together the all-purpose flour, cake flour, and cocoa powder. Turn the mixer off, and dump this into the mixer bowl. Pulse on low to moisten, then continue mixing on low until combined.
5. Remove the bowl from the mixer, scrape the dough from the paddle, and use a flexible spatula to fold the dough, ensuring there's no dry floury pockets at the bottom of the bowl.
6. Add the peanut butter swirl, or other chosen mix-ins. If using the swirl, take care to distribute it evenly but don't over-mix. You want big ribbons of it throughout, and you'll distribute it further once you start portioning the dough. If your instinct is telling you "just give it two more folds," you're wrong and your cookies will be less pretty as punishment. Learn from my mistakes.
7. Take 6 oz portions of the dough, roll them into a smooth ball taking care to maintain that marbled appearance, and place 2-3 portions on each baking sheet.
8. Bake for 14-16 minutes until only the edges have started to crack, and the tops have lost their sheen and look dry. If you're concerned about under-baking, the internal temperature should reach 150ºF. See the note above for more info on science behind choosing this internal temperature
9. Let cookies cool for 10 minutes on the pan to set, then transfer to a wire rack to cool completely.