Recipe: Chocolate Irish Cream Cheesecake

Just bought the BH&G 1998 Simply Perfect Chocolate magazine, and this was on the front cover:
Chocolate Irish Cream Cheesecake
1 cup crushed chocolate wafers (about 18 cookies)
1/4 cup melted butter (no substitutions)
1/2 tsp ground cinnamon
3 8-oz pkg cream cheese, softened
1 8-oz carton dairy sour cream
1 cup sugar
1 8-oz pkg semi-sweet chocolate, melted and cooled
3 eggs
1/3 - 1/2 cup Irish cream liqueur
2 tbs whipping cream or milk
2 tsp vanilla
Chocolate curls and leaves for garnish (optional)
1/3 cup semi-sweet chocolate pieces, melted (optional)
Crust: Combine crushed wafers, butter, and cinnamon in a medium mixing bowl; toss gently to mix. Spread mixture evenly in bottom of a 9-inch springform pan; press to form a firm, even crust. Set pan aside.
Filling: Combine cream cheese, sour cream, sugar, and the 8 oz melted chocolate in a large mixing bowl; beat with an electric mixer on medium to high speed till combined. Add eggs all at once. Beat on low speed just till combined. Stir in liqueur, whipping cream or milk, and vanilla.
Pour filling into the crust-lined pan. Place the pan on a shallow baking pan on the oven rack. Bake in a 325-degree oven for 50-60 minutes or till center appears nearly set when shaken. Cool cheesecake in pan on a wire rack for 15 minutes more. Remove sides of pan. Cool 1 hour; cover and chill at least 4 hours.
If desired, top with chocolate curls and leaves, or drizzle individual servings with the 1/3 cup melted chocolate.
Makes 12-16 servings.