Preheat your oven to 350°F (175°C).
In a double boiler or microwave-safe bowl, melt the chopped unsweetened chocolate with the butter. Stir until smooth and set aside to cool slightly.
In a mixing bowl, whisk together the eggs, sugar, and vanilla extract until well combined.
Add the melted chocolate and butter mixture to the egg mixture. Stir until everything is combined.
Gently fold in the flour and salt. Be careful not to overmix.
Pour the brownie batter into your prepared baking pan and spread it evenly. Bake for about 20-25 minutes.
While the brownies are cooling, make the ganache. Heat heavy cream until it’s just about to boil and pour it over chopped chocolate in a bowl. Stir until smooth.
Once the brownies have cooled, pour the ganache over the top and spread it evenly. Allow the ganache to set before slicing.