Fantastic Cream Cheese Fudge Brownies

1 cup margarine
4 squares unsweetened chocolate
2 cups sugar
4 eggs
2 teaspoons vanilla
1-1/2 cups flour
1/2 teaspoon salt
1-1/2 teaspoons baking powder
1 cup chopped nuts, optional
Cream Cheese Filling:
One 8-ounce package cream cheese, softened
1/4 cup sugar
1 egg
1 teaspoon cinnamon
1-1/2 teaspoons vanilla

Cream Cheese Filling: Beat ingredients in small bowl and set aside.

Brownies: Heat butter and chocolate in small pan over low heat, stirring occasionally until melted; cool. Beat chocolate mixture, sugar, eggs, and vanilla in large bowl. Add dry ingredients. Mix well; stir in nuts. Spread half of the dough in pan; spread with cream cheese filling. Gently spread remaining dough over filling. Gently swirl through dough with spoon for marbled effect. Bake at 350 degrees for 55 to 60 minutes, until toothpick inserted in center comes out clean.