Preheat oven 350 degrees and grease 13 x 9 x 2 baking dish.
In mixer, cream 1/2 cup butter. Gradually add 1 cup sugar, beating until light and fluffy. Add eggs, one at a time, beating well each time.
In a separate bowl, combine flour and salt.
Add to creamed mixture alternating with chocolate syrup (beginning and ending with flour mixture). Stir in vanilla.
Pour batter into greased pan and bake for 25-28 minutes. Cool completely.
Cream 1/4 cup butter; gradually add powdered sugar and creme-de-menthe. Mix well. Spread this mixture evenly over brownies. Chill for 1 hour.
In a double broiler, combine chocolate morsels and 1/4 cup butter; bring water to a boil. Reduce heat to low and cook until morsels are completely melted - stir constantly.
Pour chocolate mixture over brownies and chill for 1 hour.
Cut brownies into desired serving size.