In a large bowl, mix butter, sugar, and vanilla until smooth. Whisk in eggs one at a time, beating well after each addition. In a separate bowl, stir together flour, cocoa and salt. Add to butter mixture, and stirl until combined. Pour and evenly spread into a 9x13 pan lined with parchment or foil. Bake 25-30 minutes, shorter for gooer consistency.
Melt butter in a small saucepan. Whisk in cocoa, half n half, and whiskey. Add sugar 1/2 cup at a time, mixing well after each addition. Pour over brownies immediately.
Adapted from The Recipe Rebel