Preheat the oven to 180°C (350°F) and line a 9'' baking tin with baking paper.
Melt the butter and dark chocolate together.
Mix the eggs, sugar, brown sugar and vanilla extract together until the mixture becomes a light golden colour.
Mix in the chocolate mixture.
Stir in the flour and cocoa, chopped pecans and chocolate chips until just combined.
Spread the brownie mixture into an even layer.
Place in the oven to bake for 25-30 minutes. The top and sides will be set and the middle will have crumbs attached to a skewer inserted but should not be wet.
Allow to cool completely.
Pecans;
Chop the pecans into small pieces.
lace a fry pan on a medium to high heat and place the butter, salt, maple syrup, vanilla extract, cinnamon and pecans into the fry pan and fry for five minutes. Stir constantly so the pecans don't burn.
Pour onto non stick paper and spread out to allow them to cool completely.
Maple Buttercream;
Place 150g (¾ cup) of the butter, milk, maple syrup and brown sugar in a medium sized saucepan and place on a medium to high heat.
Boil the mixture for 2 minutes and then remove from the heat to cool completely in the fridge for about an hour. You could place this in the freezer to cool faster.
Once cool, add the mixture and remaining butter to a large bowl of a stand mixture and beat together.
Slowly add in the icing sugar beating until thick and creamy.
Stir through the candied pecans and spread onto the brownies.