Preheat the oven to 325˚F. Line an 8×8 baking pan with parchment paper or aluminum foil.
In a medium bowl, mix together the salt and flour.
In a separate bowl, beat together the Nutella, brown sugar, vanilla and eggs until smooth.
Alternate between adding the flour and the butter into the Nutella mixture, and blend until fully combined.
Pour the batter into the prepared pan, and bake for 50-55 minutes, or until a toothpick inserted comes out with only a couple of crumbs.
Remove from oven, and let cool for about an hour.
Meanwhile, in a large saucepan, heat the chocolate chips, peanut butter and butter until smooth. Remove from heat and mix in the rice krispies until fully combined.
Pour the rice krispies layer over the brownies, and refrigerate until cooled, around 2 hours. When cooled, slice into squares.