Chocolate Oat Bars

I made these last weekend and have been getting rave reviews from the two boys at home this week. By great restraint we've managed to keep some for guys who returned from Thailand today, thankfully it's quite a large recipe.


250g butter, melted
440g brown sugar
2 eggs, lightly beaten
2 teaspoons vanilla essence
375g self-raising flour (or plain flour plus 2 ½ teaspoons of baking powder)
3 cups rolled oats

Filling
300g chocolate, chopped
295g can sweetened condensed milk
30g butter, chopped
2 teaspoons vanilla essence
Optional: 120g chopped pecans

1. Preheat the oven to moderate (about 160C for fan forced). Lightly grease two 19cm x 29cm rectangular slice pans (or the equivalent), line with baking paper, ensuring.
2. Combine butter, sugar, eggs, and essence in a large bowl. Add sifted flour and oats; mix well.
3. Divide mixture into three equal portions. Press one portion of mixture evenly over base of one prepared pan (I found this time consuming). Repeat with other pan. Keep aside one portion. Refrigerate while preparing filling.
4. Filling: Combine chocolate, condensend milk, and butter in a small saucepan, stir over low heat for about two minutes or until chocolate is melted. Add essence and nuts, if you are using.
5. Spread filling evenly over both bases. Crumble remaining mixture over filling in both pans. 
6. Bake in a moderate oven for about 30 minutes or until browned. Cool in pans.
7. Refrigerate for several hours before cutting into slices. Either in the pans or out.