finishing salt (for topping the fully cooked brownies)
Preheat oven to 350. Grease an 8x8 baking dish or line with parchment paper.
In large bowl, mix together melted butter, oil, sugars. Add eggs and vanilla and mix well, scraping the bottom and sides of the bowl as you go.
Sift together the flour, salt, and dark cocoa powder. Add the dry mixture to the wet mixture, stirring carefully until just mixed. Be careful not to over-mix. Fold in 3/4 of the chocolate chunks.
Pour the batter into the prepared baking dish, spreading evenly. Then top with final chocolate chunks.
Bake in the oven for 35-40 minutes, until a toothpick inserted in the center comes out clean. Remove from the oven and place the pan onto cooling rack.
While the brownies are cooling, prepare the chocolate topping. Melt chocolate in a bowl for 1 minute, stopping and stirring every 20 seconds. Add the cream and butter to the melted butter and stir well.
Once the brownies have cooled a bit, pour the melted chocolate mixture over the brownies and smooth out with offset spatula. Once the topping has set a bit, top with finishing salt.
Do not cut the brownies until they are fully cooled. Using a butter knife or even a plastic knife will create cleaner lines in your brownies and will prevent a lot of the pulling that results in messy brownies.