01 - Preheat oven to 350°F. Line a 9x9-inch baking pan with parchment paper, leaving overhang for easy removal.
02 - Combine graham cracker crumbs, melted butter, sugar, and salt in a medium bowl. Press evenly into pan bottom. Bake for 10 minutes, then cool slightly.
03 - Beat cream cheese and sugar until smooth and creamy. Add eggs one at a time, mixing thoroughly after each addition. Stir in vanilla and sour cream until fully incorporated.
04 - Spread cheesecake mixture evenly over the cooled crust using a spatula.
05 - Mix diced strawberries, strawberry jam, and lemon juice in a small bowl. Drop spoonfuls over cheesecake layer and swirl gently with a toothpick or knife for marbled effect.
06 - Bake for 35-40 minutes until center is just set. Cool to room temperature, then refrigerate at least 4 hours until firm.
07 - Melt chocolate chips and butter together in microwave-safe bowl in 20-second bursts, stirring until smooth. Cool slightly before spreading.
08 - Spread chocolate over chilled bars. Once set, lift out using parchment overhang. Garnish with halved strawberries, slice into 12 bars, and serve.