Preheat oven to 325 degrees F. Grease the bottom of a 2-quart rectangular baking dish; set aside. In a medium bowl, combine oats, the 1/2 cup flour, the brown sugar, baking soda, and 1/4 teaspoon salt. Stir in the 6 tablespoons melted butter. Pat into prepared baking dish. Bake for 10 minutes.

Meanwhile, for cheesecake layer: In a small bowl, stir together cream cheese, egg yolk, and 1/4 cup of the granulated sugar; spoon in small dollops over the partially baked layer. Sprinkle with chopped nougat bars.

In a large bowl, combine the remaining 3/4 cup granulated sugar, the 1/4 cup melted butter, melted chocolate, and vanilla. Beat in egg. In a small bowl, stir together the 2/3 cup flour, the baking powder, and 1/4 teaspoon salt. Alternately add flour mixture and milk to chocolate mixture, beating with a wooden spoon after each addition just until combined. Carefully spoon over cheesecake layer. Bake for 30 to 35 minutes or until top springs back when lightly touched.

Cool in pan on a wire rack. Spread with chocolate fudge frosting. Cut into bars.

Makes: 32 bars

To Bake Ahead: Bake as directed; do not cut into bars. Cover pan; chill for up to 2 days.

Test Kitchen Tip: For a satiny finish, spread the fudge frosting on with a warm metal spatula.