Preheat oven to 350. Line a 13x9x2 inch baking pan with a 24" sheet of aluminum foil, leaving extra foil extending over ends. In a large bowl beat the butter with an electric mixer on medium to high speed until it just begins to blend and soften slightly.
Add brown sugar and salt, beat on low speed until incorporated, 30 seconds to 1 minute. With mixer off, add the 2 cups flour. Beat on low speed until flour is incorporated. Increase speed to medium, mix until ingredients from an even, cohesive dough.
Break dough into small chunks and distribute in prepared pan; with your fingers press dough into an even layer. Bake 20 minutes or until dough has begun to puff and is just set. Cool on wire rack 5 minutes.
Lightly brush exposed sides of foil with some extra softened butter to keep filling from sticking. Spread jam evenly over crust.
Sprinkle evenly with raspberries.
With a lemon zester, remove peel from lemon, making sure to avoid bitter white pith. In a large bowl, beat cream cheese with an electric mixer on medium to high speed for 30 seconds. Mix in granulated sugar and 1 T flour until blended. With mixer running, add egg, egg yolk, lemon zest, lemon juice and vanilla. Beat until smooth.
Pour custard batter evenly over berries. Tilt pan back and forth to distribute evenly. Bake at 350 for 25 to 30 minutes or until barely set. Transfer to a wire rack until completely cool, about 1 hour; cover and transfer to refrigerator. Chill 2 hours. Top will crack slightly as it cools.
Use foil to lift the bars from pan. With a knife or metal spatula, support the sides of the bars while you gently peel the foil downward and away from sides of the bars.
Cut into long bars, peel foil from bottom, and transfer to cutting boards using side of a long knife or spatula. Cut into 24 squares.