Dulce de Leche Bars (with Chocolate)

I got this recipe around the holidays from one of my supervisors and have been dying to try it.  My sister in law got the can of Dulce de Leche from some little shop in NYC since I couldn't find it anywhere around here.  To be honest, I'm wondering if just a normal can of sweetened condensed milk wouldn't taste the same in this considering the Dulce de Leche looked, smelled, and tasted pretty much the same to it.  Either way... delish :)  This was a Happy Mothers Day to me treat ;)

1 1/2 c all purpose flour
1 1/2 c oats (old fashioned or quick cooking)
1 c packed brown sugar
1/4 tsp salt
1 c butter, softened
1 can (13.4oz) dulce de leche
1 c toffee bits
1 c semi sweet chocolate morsels (optional-not in the original recipe but of course, chocolate makes everything better)

Preheat oven to 350 F.  Mix flour, oats, brown sugar and salt in a large bowl.  With a pastry blender or fork (I used my hands actually) cut in butter until mixture is crumbly.  Press 3/4 of the mixture into the bottom of a greased 13x9 pan.  Bake 10 minutes.  In a 1 quart sauce pan heat dulce de leche over low heat 2 to 4 minutes stirring frequently until softened.  Spread dulce de leche over top of partially baked crust and sprinkle evenly with toffee bits (and chocolate if using).  Top with remaining crumb mixture.  Bake 20 to 25  minutes or until golden brown.  Cool 15 minutes.  Run knife around side of pan to loosen.  Cool completely and cut into 32 bars.