Preheat oven to 350 degrees.
Cream butter, sugar, and cacao together.
Add in eggs and vanilla.
Add flour and salt. Mix thoroughly.
Spread evenly in a greased cookie sheet.
Bake for 25 minutes.
Melt butter in a small saucepan.
While still over the heat, add in cacao, salt, and vanilla.
Once well incorporated, add powdered sugar. Use a whisk to mix and add a little bit of cream at a time until desired consistency is reached.
When the brownies are cool, spread the frosting over the brownies.