📖 Instructions

1. Gather all your ingredients and equipment. Before you start anything, it's a good idea to lay everything out on your counter. This ensures you won't be scrambling for an ingredient in the middle of mixing, and it helps you visually confirm you have everything you need. Preheat your oven to 375°F (190°C) and line a standard 12-cup muffin tin with paper liners. Make sure the liners sit snugly in each cup.
2. In a small, microwave-safe bowl, combine the unsalted butter and unsweetened chocolate. Heat in the microwave in 30-second intervals, stirring well after each, until both are completely melted and smooth. This usually takes about 1-2 minutes. Set this mixture aside to cool slightly while you prepare the other components.
3. In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, cocoa powder, baking soda, and a pinch of salt. Use a whisk to ensure there are no lumps and that all the dry ingredients are thoroughly combined. This step is crucial for an evenly textured muffin.
4. In a separate, medium-sized bowl, lightly whisk the large eggs. Add the milk and vanilla extract to the eggs and whisk until just combined. You don't need to create a lot of foam here, just enough to break up the yolks and integrate the milk and vanilla.
5. Pour the slightly cooled melted chocolate and butter mixture into the wet ingredients (eggs, milk, vanilla). Whisk gently until everything is fully incorporated. Make sure the chocolate mixture isn't too hot, or it might cook the eggs prematurely.
6. Create a well in the center of your dry ingredients. Pour the chocolate-egg-milk mixture into this well. With a rubber spatula, gently fold the wet ingredients into the dry ingredients until just combined. The batter will be thick, almost like brownie batter, and it's okay if there are a few small streaks of flour remaining. The key here is not to overmix! Overmixing develops the gluten too much, leading to tough, dense muffins.
7. Spoon about 1-2 tablespoons of the muffin batter into the bottom of each prepared muffin liner. This layer will form the base of your muffin and help cradle the cookie.
8. Carefully place one mini chocolate chip cookie (or a standard-sized one broken in half) on top of the batter in each muffin cup. Gently press it down a little, but don't submerge it completely. This is your delicious surprise!
9. Top each cookie with another 1-2 tablespoons of muffin batter, ensuring the cookie is completely covered. You want the batter to reach about two-thirds full in each muffin liner.
10. If you want extra chocolate goodness (and who doesn't?), sprinkle a few extra chocolate chips on top of each muffin before baking. This also gives a lovely visual cue to the deliciousness within.
11. Place the muffin tin into the preheated oven. Bake for 18-22 minutes. The exact time can vary depending on your oven, so keep an eye on them.
12. To check for doneness, insert a toothpick into the center of a muffin. If it comes out with moist crumbs but no wet batter, they are ready. If it comes out completely clean, they might be slightly overbaked, but still delicious.
13. Once baked, remove the muffin tin from the oven. Let the muffins cool in the tin for about 5 minutes. This allows them to set up slightly before you move them.
14. Carefully transfer the muffins from the tin to a wire rack to cool completely. While they are tempting to eat right away, letting them cool fully helps them firm up and intensifies their flavor. However, a warm one is pretty glorious too, so I won't tell if you sneak one!
15. Serve warm or at room temperature. These muffins are best enjoyed on the day they're made, but they can be stored in an airtight container for up to 3 days.