Start by breaking the 4 ounces of unsweetened chocolate into small pieces and placing them in a microwave-safe bowl along with the 3/4 cup of unsalted butter. Microwave in 30-second intervals, stirring in between, until completely melted and smooth. This should take about 1 to 2 minutes.
Once the chocolate and butter are melted and combined, add in the 1 and 3/4 cups of sugar. Stir until the mixture is well combined and glossy.
Next, crack in the 3 eggs one at a time, mixing well after each addition. Then, add the 1 teaspoon of vanilla extract, stirring until fully incorporated.
Gently fold in the 1 cup of all-purpose flour until just combined. Be careful not to overmix, as this can lead to dense brownies.
Finally, fold in the 1 cup of chopped pecans. If you chose to toast them, make sure they’ve cooled slightly before adding them to the batter.
Preheat your oven to 350°F (175°C). Pour the brownie batter into a greased 9x9-inch baking pan, spreading it evenly. Bake for 25-30 minutes or until a toothpick inserted into the center comes out with a few moist crumbs. Allow them to cool in the pan for at least 10 minutes before transferring to a cooling rack.