Preheat oven to 350 degrees F. Butter or grease a 13- by 9-inch baking pan.
In a large bowl, beat butter until creamy. Beat in flour and brown sugar until well mixed. With floured fingers, press 1 3/4 cups crumb mixture onto bottom of prepared baking pan; reserve remaining mixture. Bake approximately 10 to 12 minutes or until edges are golden brown; remove from oven and set aside.
In a small saucepan over low heat, combine 1/2 cup semisweet chocolate chips, 1/2 cup bittersweet chocolate chips, and sweetened condensed milk. Melt over low heat, stirring until smooth. Remove from heat and spread over prepared hot crust.
Stir chopped nuts into reserved crumb mixture; sprinkle over chocolate filling. Drop, by teaspoons, raspberry jam over the crumb mixture. Sprinkle with remaining 1 cup semisweet and bittersweet chocolate chips.
Return to oven and continue baking for 25 to 30 minutes or until center is set. Remove from oven and let cool in the pan on a wire cooling rack. Once cool, cut into bars.
* If desired, more raspberry jam may be used. Also you could use any flavor of jam you prefer.
Chocolate Raspberry Crumb Bars Recipe: https://whatscookingamerica.net/cookie/chocraspberrycrumbbars.htm