Brownie Bottom Cheesecake

1/2 cup (1 stick) butter or margarine
4 (1 ounce) squares unsweetened chocolate
2 1/4 cups granulated sugar, divided
2 eggs
1/4 cup milk
2 teaspoons vanilla extract, divided
1 cup flour
1/2 teaspoon salt
24 ounces cream cheese,
softened 3 eggs 1/2 cup sour cream

method;

Melt butter and chocolate in a 3−quart heavy saucepan on very low heat, stirring constantly. Cool. Blend in 1 1/2 cups of the sugar.Add two of the eggs, one at a time, mixing on low speed after each addition until blended. Blend in milk and 1 teaspoon of the vanilla extract.

Mix flour and salt. Add to chocolate mixture, mixing just until blended. Spread evenly onto bottom of greased and floured 9−inch springform pan. Bake at 325 degrees F for 25 minutes.
Mix cream cheese, remaining 3/4 cup of sugar and 1 teaspoon of vanilla extract with electric mixer on medium speed until well blended. Add remaining three eggs, one at a time, mixing on low speed after each addition just until blended. Bland in sour cream; pour over brownie bottom. (Filling will almost come to top of pan.)

Bake at 325 degrees for 55 minutes to 1 hour or until center is almost set. Run knife or metal spatula around rim of pan to loosen cake; cool before removing rim of pan. Refrigerate for four hours or overnight.
Let stand at room temperature 30 minutes before serving.
Drizzle with assorted ice cream toppings, if desired.