Start by preheating your oven to 350°F (175°C). While it heats, line a 9x13-inch baking pan with parchment paper, letting the edges overlap slightly so you can lift the finished brownies out easily. This saves cleanup time and prevents any sticking that would ruin your beautiful brownies. Parchment paper is non-negotiable for meal prep—it lets you remove the entire brownie slab at once, cool it completely flat, and then cut perfect squares without fussing.

Pour 1 cup of melted unsalted butter into a large mixing bowl and let it cool for 3-5 minutes. You want it warm enough to combine easily with the other ingredients, but cool enough that it won't scramble your eggs. This is a professional detail that makes a real difference in texture. If your butter is too hot, the eggs will cook slightly, and you'll get a less fudgy crumb.

To the cooled butter, add 2½ cups of granulated sugar and whisk vigorously for about 2 minutes until the mixture is slightly pale and combined. This whisking step is where you're incorporating air, which gives brownies their structure. Next, add 4 room-temperature eggs one at a time, whisking after each addition. Finish with 1 tablespoon of pure vanilla extract. The mixture should look rich and well-blended.

In a separate bowl, sift together 1½ cups of all-purpose flour, 1 cup of unsweetened cocoa powder, ½ teaspoon of fine sea salt, and ½ teaspoon of baking powder. Sifting removes lumps in the cocoa and distributes the leavening evenly—you're building structure here. Gently fold the dry mixture into your wet mixture using a rubber spatula, stirring just until you don't see streaks of flour. Overmixing creates dense brownies—stop as soon as it's combined.

Pour your batter into the prepared pan and use an offset spatula to smooth the top evenly. This ensures even baking across the entire batch. Bake for 28-32 minutes—they should be set on top but still slightly soft in the center (a toothpick inserted in the middle should have a few moist crumbs, not come out clean). Underbaking slightly is intentional here; you want fudgy, not cake-like.

Let the brownies cool in the pan for 15 minutes, then use the parchment paper overhang to lift the entire slab onto a wire cooling rack. This prevents the bottom from steaming and becoming soggy. Let them cool completely—at least 2 hours at room temperature. Patience is critical for meal prep; cutting warm brownies creates crumbles and uneven pieces.

Using a sharp chef's knife (wiped clean between cuts if the blade gets sticky), cut the cooled brownie slab into 12 equal squares. A 9x13 pan cuts beautifully into a 4x3 grid. Place each brownie in a parchment-lined storage container or wrap individually in plastic wrap for portioning throughout the week.