lion house oatmeal fudge bars

i made these the other night for a party.  they were a huge hit!

makes 36 bars
1 cup butter or margarine, softened
2 cups packed brown sugar
2 eggs
2 teaspoons vanilla
2½ cups all-purpose flour
1 teaspoon baking soda
½ teaspoon salt
1½ cups quick-cooking rolled oats
1 (14-ounce) can sweetened condensed milk
1 (12-ounce) package semisweet chocolate chips
¼ cup margarine
2 teaspoons vanilla
1 cup chopped walnuts, optional

preheat oven to 350 degrees f. grease a 9 × 13-inch baking pan and set aside.
cream together butter and brown sugar in a large mixing bowl; add eggs and vanilla. sift flour, baking soda, and salt into a small bowl, and then add to creamed mixture. mix in oats.
combine sweetened condensed milk, chocolate chips, and margarine in a heavy saucepan, and heat until chocolate is just melted. stir in vanilla and nuts.
spread two-thirds of the dough into prepared baking pan. spread with chocolate mixture. drop remaining one-third of dough on top by spoonfuls. bake 25 minutes. cool and then cut into bars.