Preheat oven to 350°F. Grease or spray the bottom and sides of a 13x 9-inch baking pan.
In a large bowl, place cake mix, butter, cream cheese and egg. Using an electric mixer on medium speed, beat 2 to 3 minutes, stopping once to scrape down the bowl. Press dough into the bottom of the prepared pan. Drop spoonfuls of jam over the surface of the dough. In a small bowl, combine walnuts, sugar and cinnamon; sprinkle evenly over jam and dough.
Bake 18 to 23 minutes, until golden brown at edges and a toothpick inserted near the center comes out with moist crumbs attached.
Let cool completely on a rack. Cut into triangles.