Heat oven to 350°F. Line an 8-inch square pan with parchment, leaving overhang.
Melt butter and chopped chocolate in a saucepan over low heat, stirring until smooth. Cool 5 minutes.
Whisk in granulated and brown sugars until glossy. Beat in eggs one at a time, then add vanilla.
Sift flour, cocoa, and salt over the bowl. Fold just until no dry streaks remain.
Beat cream cheese with 1/4 cup sugar, 1/2 tsp vanilla, and the yolk until smooth and creamy.
Warm raspberry jam with lemon juice until loosened and spoonable.
Spread about two-thirds of the brownie batter in the pan. Dollop cream cheese and jam over the top.
Spoon remaining batter in mounds. Swirl everything together with a knife for a marbled pattern.
Bake 32–38 minutes, until edges are set and a toothpick comes out with a few moist crumbs.
Cool completely on a rack. Chill 30 minutes for the cleanest slices. Garnish with raspberries, if using.
Notes
Variation: Add 1/2 cup white chocolate chips to the batter for a sweeter contrast, or swap in blackberry jam. Storage: Refrigerate in an airtight container up to 5 days; freeze tightly wrapped for 2 months.This recipe is an original creation inspired by classic Raspberry Cream Cheese Brownies flavors. All ingredient ratios and instructions are independently developed.