Ingredients:
Caster sugar 1 cup
Butter (softened) 1/2 cup
Eggs 4
Chocolate syrup 1-1/2 cups
Flour 1 cup
Icing sugar 2 cups
Butter (softened) 1/2 cup
Mint essence 1 tsp
Butter 6 tbsp
Chocolate (chopped) 1 cup

Method:
Beat ½ cup butter and 1 cup sugar until smooth. Beat in eggs one at a time, then stir in the chocolate syrup. Stir in the flour until just blended. Spread the batter evenly into a greased 9x 13 baking dish. Bake for 25 to 30 minutes at 180 degrees C, or until top springs back when lightly touched. Cool completely in the pan. In a small bowl, beat the icing sugar, 1/2 cup butter and mint essence until smooth. Spread evenly over the cooled brownies, then chill until set. Melt the remaining 6 tablespoons of butter and the chocolate, stirring occasionally until smooth. Allow to cool slightly, then spread over the top of the mint layer. Cover, and chill for at least 1 hour before cutting into squares.