Preheat the oven to 180C. Line a 20x20x baking tin with baking parchment.
Dice the butter and break the chocolate into small pieces. Put them in an oven-proof dish and put this into the warming oven to melt.
Grate the beetroot.
Mix the eggs with the sugar, add the melted chocolate and butter, then add the flour, salt and the grated beets.
Stir gently a couple times. It is important not to over-mix the batter, otherwise the brownies will be hard.
Transfer the batter into the tin and spread out evenly .
Bake for 20 minutes then let it cool in the tin.
When completely cooled, cut into squares.