Preheat the oven to 175 degrees C top / bottom heat.
In a large bowl, mix the butter, sugar, cocoa powder and eggs. Add the flour, vanilla extract, salt and nuts and stir well. Pour the batter into a brownie pan and put the pan in the oven. Bake the dough for about 20 minutes, make a stick test.
Take the brownies out of the oven and let them cool down a little.
Frosting:
Mix all ingredients, spread on the brownies and cut them after 1 hour.