Prep the pan and oven: Heat the oven to 350°F (175°C). Line an 8-inch square pan with parchment, leaving overhang for easy lifting. Lightly grease the parchment.

Combine wet ingredients: In a large bowl, whisk 1/2 cup (113 g) melted unsalted butter with 2 tablespoons neutral oil. Add 3/4 cup (150 g) granulated sugar and 1/2 cup (100 g) light brown sugar. Whisk until glossy and slightly thick, about 30–45 seconds.

Add eggs and vanilla: Whisk in 2 large eggs, one at a time, until fully incorporated. Stir in 2 teaspoons vanilla extract. The mixture should look smooth and shiny.

Whisk dry ingredients: In a separate bowl, whisk 3/4 cup (90 g) all-purpose flour, 1/2 cup (45 g) unsweetened cocoa powder, 1/2 teaspoon fine sea salt, and 1/4 teaspoon baking powder. If using, add 1 teaspoon espresso powder for deeper flavor.

Fold together: Add dry ingredients to the wet. Use a spatula to fold until just combined. Stop when no dry streaks remain; overmixing makes brownies tough.

Add chocolate chips: Fold in 1 cup (170 g) semi-sweet chocolate chips, reserving a small handful to sprinkle on top.

Pan and bake: Scrape the batter into the prepared pan and smooth the top. Sprinkle on the reserved chips. Bake 22–28 minutes, until the edges are set and the center is slightly soft. A toothpick should come out with a few moist crumbs, not wet batter.

Cool: Set the pan on a rack and cool completely, at least 1 hour. For the cleanest slices, chill 20–30 minutes after cooling, then lift out and cut with a sharp knife, wiping the blade between cuts.

Serve: Enjoy as is, or warm briefly and top with ice cream. A pinch of flaky sea salt on warm brownies is excellent.