Party Sized Brownie Recipe

Prepare oven and pan

Preheat the oven to 350°F (175°C). Line a 13x18-inch half-sheet pan (party size) with aluminum foil or parchment, leaving an overhang on two sides for easy lifting. Lightly butter or spray the lining.

Melt butter and chocolate

Place the chopped chocolate and butter in a heatproof bowl set over a pot of simmering water (double boiler) making sure the bowl doesn't touch the water, or use a microwave in 30-second bursts, stirring until smooth. Remove from heat and let cool slightly (3–5 minutes).

Combine sugars and chocolate

Whisk the granulated and brown sugars into the slightly cooled chocolate mixture until well combined. This helps partially dissolve the sugar and yield a glossy batter.

Add eggs and vanilla

Whisk in the eggs one at a time, fully incorporating each before adding the next, then whisk in the vanilla until the mixture is smooth and slightly thickened.

Sift and fold dry ingredients

Sift together the flour, cocoa powder, baking powder, and salt into a large bowl. Add about one third of the dry mixture to the chocolate-egg mixture and fold gently with a spatula to combine. Repeat with the remaining dry ingredients in two additions, folding until no streaks remain. Avoid overmixing to keep the brownies tender.

Add mix-ins

Fold in the chopped nuts and/or chocolate chips if using, reserving a handful to sprinkle on top for appearance.

Transfer to pan

Pour and spread the batter evenly into the prepared half-sheet pan, using an offset spatula to smooth the surface. Sprinkle reserved chocolate chips/nuts on top and finish with a light scattering of sea salt flakes if desired.

Bake

Bake in the preheated 350°F (175°C) oven for 20–28 minutes. Start checking at 20 minutes: brownies are done when the edges are set, the center still looks slightly gooey, and a toothpick inserted into the center comes out with moist crumbs (not wet batter). Baking time will vary by oven and pan thickness.

Cool

Remove the pan from the oven and set on a wire rack. Let cool completely in the pan (about 1–2 hours) to firm up and allow clean slicing. If you want faster cooling, place the pan uncovered in a cool area or briefly in the fridge after it reaches warm temperature.

Slice and serve

Using the foil/parchment overhang, lift the brownie slab from the pan and place on a cutting board. Use a sharp knife warmed under hot water and wiped dry between passes for clean cuts. Slice into approximately 5x6 rows to make 30 party-sized brownies, or cut to preferred size. Serve at room temperature; store any leftovers in an airtight container for up to 3 days (refrigerate in warm climates).