Preheat oven to 200C/180C Fan/Gas 6. Line a 8″ square baking tin with greaseproof paper.
Melt the dark chocolate by breaking up into small pieces in a bowl and heating for 30 second intervals in a microwave, stirring in between. Set aside to cool whilst making the brownies.
In a large bowl or the bowl of a stand mixer combine the butter, and both the brown and granulated sugars on a medium speed until totally combined.
Add the eggs, vanilla and maple syrup and mix again. Then check that the chocolate has cooled a little before adding in and combining.
Add in the flour and cocoa powder, and fold together. Add in the chocolate chunks and pecans. Stir to combine.
Pour the mixture into the baking tin and bake for 30 minutes.
Remove and let cool on a wire rack. Once cool, make the glaze by combining the ingredients in a small bowl. Adjust consistency to taste with milk/icing sugar. Drizzle over and scatter any remaining crushed pecans. Slice and serve!