Preheat the oven to 350. Prepare a 9 x 9 or 8 x 8 baking dish by lining with foil or parchment paper.
In a large bowl or the bowl of a stand mixer, cream together the butter and sugar until light and fluffy.
Add the vanilla and eggs and mix until combined.
Add the flour, cocoa powder, baking powder, and salt, and stir until combined.
Spread the mixture in the prepared pan and bake 20-25 minutes, or until a toothpick inserted two inches away from the side of the pan comes out clean.
Let cool completely.
To make the frosting, beat together the butter, powdered sugar, salt, and vanilla until combined.
Add the chocolate hazelnut spread and beat until light and fluffy.
Spread on the cooled brownies and enjoy!