Preheat oven to 350°F. Lay aluminum foil or parchment paper overhanging an inch or two on opposite edges of a 9-inch square baking pan. Grease the liner lightly.
Step 2
Put butter and chocolate in a large microwave-safe bowl. Half-power microwave in 30-second intervals until butter and chocolate melt when swirled. Stir smooth. Allow to cool slightly.
Step 3
Next, whisk in the cocoa powder, sugar, eggs, and vanilla. Whisk in flour, cinnamon, and salt. Mix in pecans. Sprinkle a couple teaspoons of nuts over the batter if desired.
Step 4
Spread batter in prepared pan. Sprinkle reserved pecans over batter. Apply pressure lightly.
Step 5
Bake for 35–40 minutes until the edges are firm and a pick inserted into the center comes out with crumbs.
Step 6
On a wire rack, cool brownies in the pan. Remove the brownies from the pan using the overhanging liner. Cut and serve squares.