1. Preheat oven to 350º F. Line a 13X9 inch baking pan with foil; leaving enough overhang on the short sides to be used as a handle to lift bars from the pan. Spray the foil with non-stick cooking spray.
2. In the bowl of a full sized food processor, combine flour, brown sugar and salt. Pulse until everything is evenly distributed. Cut the sticks of cold butter into ¼ inch pats. Add one half the butter to the processor bowl and pulse a couple of times. Add the remaining butter and pulse until the crumb mixture is even is size. (If you don’t have a full size food processor, you may do this by hand. Combine dry ingredients in a large mixing bowl; stir until evenly combined. Add pats of cold butter to the dry ingredients and process with a pastry blender until the crumb mixture is even in size.)
3. Press approximately 1-3/4 cups of crumb mixture evenly onto the bottom of the foiled pan.
4. Bake for 10-12 minutes until the edges of the crumb crust is a golden brown.
5. While the crust is baking, microwave the sweetened condensed milk and 1 cup of the chocolate chips for 1 minute on high. Stir until the chocolate mixture is completely melted and smooth. If there are still some un-melted chips, you can microwave for an additional 10 seconds; you may have to repeat this a couple of times. Just be sure to stir at each 10 second interval. You don’t want to scorch the chocolate.
6. Spread the chocolate mixture evenly over the hot crust. If you are using nuts, stir them into the remaining crumb mixture. Sprinkle the rest of the crumb mixture evenly over the layer of chocolate. On top of the crumb mixture drop the raspberry jam or preserves by the teaspoon evenly. Sprinkle the remaining chocolate chips over the raspberry and crumb topping. You may use up to 1 additional cup of chips. I feel that ¾ of a cup is sufficient, but you may want more or less; look at the Raspberry Chocolate ratio and decide for yourself.
7. Bake for 25 to 30 minutes or until the crumb topping is golden. Cool the pan completely on wire rack. Pull the Raspberry Chocolate bars by the foil handles and place onto a cutting board. With a sharp knife, cut into bars.