A classic childhood recipe for yummy chocolate revel brownies.
Preheat oven to 350F.
Line a 10 x 15 inch baking pan with parchment paper or foil.
Set aside 2 tablespoons of the butter for later. In a large mixing bowl beat the remaining butter with an electric mixer on medium speed for 30 seconds.
Add brown sugar; beat until well mixed. Beat in eggs and 2 teaspoons vanilla. In another large bowl stir together flour and baking soda; stir in oats.
Gradually stir dry mixture into beaten mixture. Set aside.
In a medium saucepan combine the reserved butter, the sweetened condensed milk, and chocolate pieces. Cook over low heat until chocolate melts, stirring occasionally. Remove from heat. Stir in walnuts and the 2 teaspoons vanilla.
Press two-thirds (about 3-1/3 cups) of the oat mixture into the bottom of prepared baking pan.
Spread chocolate mixture over the oat mixture. Using a spoon to dot remaining oat mixture over the chocolate.
Bake for 25 minutes or until top is lightly browned.
Cool on a wire rack entirely before cutting.