Preheat oven to 350 degrees and grease cookie sheet(s) well.
Combine chocolate and butter in a saucepan over a double boiler. Bring water to a boil and reduce the heat to low. Cook and stir until the chocolate and butter melt. Take off stovetop. (Note: If you don’t have a double boiler, feel free to put the chocolate and butter in a microwave-safe bowl and microwave for 1 minute, stopping the microwave to stir the mixture after 30 seconds.)
In the large bowl of a stand mixer, beat the eggs with whisk attachment until they are foamy, and then gradually add the brown sugar. Beat until mixture is thick, about 5 minutes. Pour melted chocolate mixture into the egg mixture.
In a separate mixing bowl combine the flour, salt, and baking powder. Add the dry ingredients to the egg mixture. Stir brownie batter until well blended, add the vanilla, and then fold in the pecans with a spatula.
For best results, refrigerate the cookie dough for at least 30 minutes before baking. You can refrigerate overnight.
Scoop cookie dough on a well-greased baking pan in teaspoon-sized dollops, 2 inches apart. Bake at 350 degrees for 7-9 minutes or until the cookies are set. Let cookies cool on cookie sheet for about 5 minutes before transferring to a wire rack to complete cooling.