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

Toast the pecans: Spread pecans on a baking sheet and toast for 6–8 minutes until fragrant. Cool slightly, then chop roughly if you prefer smaller pieces.

Make the brownie batter: Melt 1/2 cup (1 stick) butter in a saucepan over low heat. Remove from heat and whisk in 3/4 cup granulated sugar and 1/4 cup brown sugar. Whisk in 2 large eggs, one at a time, then 1 teaspoon vanilla.

Add dry ingredients: Sift in 1/2 cup cocoa powder, 1/2 cup all-purpose flour, and 1/2 teaspoon salt. Stir just until you see no dry streaks. Fold in 1/2 cup dark chocolate chips if using.

Bake the base: Spread batter into the pan. Bake for 18–20 minutes, until the top looks set and a toothpick comes out with moist crumbs (not wet batter). Set aside while you make the topping. Keep the oven at 350°F.

Cook the pecan topping: In a medium saucepan, melt 4 tablespoons butter. Stir in 1/2 cup brown sugar, 1/3 cup maple syrup (or light corn syrup), and a pinch of salt. Bring to a gentle bubble over medium heat, stirring for 2–3 minutes until glossy. Remove from heat and whisk in 2 tablespoons heavy cream and 1 teaspoon vanilla. Fold in 1 1/2 cups toasted pecans.

Top and finish baking: Pour the pecan mixture over the brownie base and spread evenly. Bake 15–18 minutes, until the topping is set at the edges and just slightly jiggles in the center.

Cool completely: Let the pan cool on a rack for at least 2 hours. For clean slices, chill 30–60 minutes before cutting.

Slice and serve: Use the parchment to lift out the slab. Cut with a sharp knife, wiping the blade between cuts. Serve at room temperature or slightly chilled.