In a medium saucepan over medium-low heat melt the butter and cocoa.
Remove from the heat, stir in the sugar. Blend the eggs in one at a time. Add the vanilla and stir in.
Stir in the flour. When the flour is combined stir in the mint chocolate chips.
Spread the batter into a 9 by 13-inch pan. Bake at 350 degrees F for 25 to 30 minutes. Be careful not to over bake. Remove from the oven and cool completely.
While the brownies are cooling make the frosting.
In a medium bowl add the egg whites, shortening, and butter. With an electric mixer beat together.
Mix in the vanilla. Add the powdered sugar and salt and beat in. (If the frosting is too soft add additional powdered sugar).
Add the mint extract no more than 1/4 teaspoon and blend in. If you desire more mint flavor add the remaining 1/4 teaspoon. For the food coloring add only a little at a time until the desired color.
Spread the frosting over the cooled brownies.
For the chocolate mint drizzle combine - 2/3 cup of chocolate mint chips, corn syrup, and milk into a small saucepan. Over low heat melt the ingredients until the chocolate is melted and creamy.
Drizzle the melted chocolate over the top of the brownies.