Prepare a 8" x 8" pan by lining with parchment paper. Leave extra so you can easily lift squares out of pan. Preheat oven to 350ºF.
In a bowl beat margarine and sugar until light and fluffy. Stir in flour and rolled oats until mixture comes together (you may use your hands).
Press mixture into prepared pan firmly. Bake for 25 minutes until golden. Allow to cool.
Place ingredients for Caramel layer in a small pan and heat gently, stirring until the sugar is dissolved. Bring to a boil over very low heat (this will take 4-5 minutes), boil, stirring constantly for 3-4 minutes until mixture has thickened.
Pour caramel over oatmeal cookie crust and allow to set for 10-15 minutes.
Melt chocolate chips then spread over caramel.
Melt white chocolate and pipe in lines over dark chocolate. Using a toothpick drag through the dark chocolate in opposite direction to create pattern. Let set completely before cutting into squares. Can be stored in refrigerator or on countertop.