Technically “baking cookies” in a slow cooker is a misnomer. You’ll need not turn on the oven nor dirty your cookie scoop, nor pull out your sheet pans, for this recipe. The ingredients are fairly standard otherwise: flour, sugar (white and dark brown), butter, eggs, vanilla. There’s an extra yolk for added moisture—though the final texture of this cookie is more akin to a cakey blondie than a crispy Tate’s cookie or chewy Toll House. When it comes to chocolate, I’m of the mindset that the darker, the better (at least 60%), but any blend of chopped chocolate—milk, semisweet, bittersweet, white, etc.—can also be quite exciting. Check the size of your slow cooker: this recipe was developed for a 6-quart slow cooker. If yours is larger or smaller the cook time may vary. —Rebecca Firkser
Grease the bowl of a 6-quart slow cooker with cooking spray. Cut two 4-inch wide strips of parchment paper, place one in the slow cooker, give it another spritz of cooking spray, then lay down the other strip of parchment over it in the opposite direction, like a “+”.
In a small bowl, whisk together flour, baking soda, and salt. Set aside.
In a large bowl using a whisk or a hand mixer, or in the bowl of an electric stand mixer, cream together the butter and sugars at medium speed for about 5 minutes, or until lightened in color and fluffy. Scrape down the sides of the bowl and beat in eggs one at a time, waiting until the first is completely mixed in before beating in the second. Beat in the egg yolk. Beat in the vanilla.
Mix in the flour mixture in 3 batches using a spoon until just combined, then fold in the chopped chocolate.
Press the batter into prepared slow cooker, using an offset spatula to smear it into an even layer, and cover with lid. Cook on high for 1 1/2-2 hours or on low for 3 1/2-4 hours. The cook time will ultimately depend on the size and power of your slow cooker. The cookie should be fully cooked with a slightly molten center, which is perfect if you want to eat this cookie like spoonbread. If you want to slice the cookie into bars, cook for an additional 15-30 minutes on high (again, this time will ultimately depend on the size and power of your slow cooker model), until edges are golden brown but not starting to burn.
Turn off the slow-cooker, and use potholders to transfer the insert to a cooling rack. Cool for at least 15 minutes, then remove from the insert by lifting up the exposed parchment strips. Discard parchment. Shower cookie with flaky sea salt and serve whole with a big scoop of ice cream on top and a pile of spoons. If you’re civilized, cut into slices like cake instead. If baked longer or in advance, cut the cookie into bars and store in an airtight container for up to 1 week.
Rebecca Firkser is a freelance food writer and recipe developer. Her work has appeared in a number of publications, among them Food52, TASTE, Edible Manhattan, Extra Crispy, The Strategist, and Bon Appetit's Healthyish. She contributed recipes and words to the book "Breakfast: The Most Important Book About the Best Meal of the Day." Once upon a time, she studied theatre design and art history at Smith College, so if you need a last-minute avocado costume or want to talk about Wayne Thiebaud's cakes, she's your girl.