Preheat the oven to 325 degrees F. Spray a 9x13 inch pan with nonstick spray.
In a glass bowl, melt the chocolate and butter together in a microwave (or melt in a double boiler set over hot water). Whisk until smooth.
In a medium bowl, use an electric mixer to combine the eggs and sugar. Mix for a good three solid minutes until mixture is very thick. Mix in the melted chocolate and butter. Add the flour and vanilla, and mix just until combined.
Pour the batter evenly into the prepared pan. Bake for 30 minutes or until a toothpick inserted in the center comes out clean. Set aside to cool.
FROSTING
Melt chocolate and butter together, and whisk until smooth.
In a medium bowl, use an electric mixer to combine the powdered sugar, half and half, whiskey and vanilla. Add the melted chocolate and butter, and beat until smooth. Spread the frosting over the cooled brownies.
Notes
I like to chill these brownies completely before cutting.