Preheat the oven to 300 degrees F (150 degrees C). Line a 9x13-inch pan with greased parchment paper.

Place sugar, cocoa, flour, melted butter, eggs, vanilla, and salt in a large bowl. Mix until well combined; it will be thick and sticky. Spread brownie batter into the prepared pan.

Bake in the preheated oven for 30 minutes. Cool completely; cut into squares and dust with confectioners’ sugar.