These Raspberry Cheesecake Brownies require attention to detail and patience, but the results are well worth the effort. The key to success is maintaining distinct layers while creating a beautiful swirl pattern on top. Take your time with each step, particularly when it comes to proper cooling and chilling.

1. Step 1: Proper pan preparation is crucial for clean removal of these layered brownies.

   Preheat your oven to 325°F (165°C). Line a 9x13-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal. Lightly butter the parchment paper.

2. Step 2: Be careful not to overheat the chocolate or it may seize.

   In a large heatproof bowl set over a pot of barely simmering water (double-boiler method), melt the butter and chopped chocolate together, stirring occasionally until completely smooth. Remove from heat and let cool slightly.

3. Step 3: Adding eggs one at a time ensures proper incorporation and a smoother batter.

   Whisk 1 cup of granulated sugar and the brown sugar into the chocolate mixture until well combined. Add 4 eggs, one at a time, whisking well after each addition. Stir in 1 teaspoon of vanilla extract.

4. Step 4: Overmixing can lead to tough brownies. Stop folding as soon as no dry streaks remain.

   In a separate bowl, whisk together the flour, cocoa powder, and salt. Gently fold the dry ingredients into the chocolate mixture until just combined. Do not overmix.

5. Step 5: An offset spatula works best for creating an even layer.

   Pour the brownie batter into the prepared pan, spreading it evenly with a spatula. Set aside while preparing the cheesecake layer.

6. Step 6: Room temperature cream cheese is essential for a smooth, lump-free cheesecake layer.

   In a stand mixer fitted with the paddle attachment (or using a hand mixer), beat the cream cheese on medium speed until completely smooth, about 2 minutes. Add the remaining 1/2 cup of granulated sugar and beat until combined.

7. Step 7: Overmixing can incorporate too much air, which may cause cracks in the cheesecake layer.

   Add the remaining 2 eggs one at a time, beating well after each addition. Mix in the sour cream and remaining 1 teaspoon of vanilla extract until smooth and creamy. Be careful not to overmix.

8. Step 8: Pour slowly to maintain distinct layers.

   Carefully pour and spread the cheesecake mixture over the brownie batter in the pan, creating an even layer.

9. Step 9: Don't overswirl or you'll lose the distinct raspberry pattern.

   Warm the raspberry preserves in the microwave for 15-20 seconds until slightly fluid. Drop spoonfuls of the preserves over the cheesecake layer. Use a toothpick or skewer to swirl the preserves through the cheesecake layer, creating a marbled effect.

10. Step 10: A slight wobble in the center indicates perfect doneness - it will set as it cools.

    Bake in the preheated oven for 45-50 minutes, or until the edges are set but the center still has a slight jiggle. The cheesecake layer should not be completely firm.

11. Step 11: Patience is key - proper cooling and chilling ensures clean cuts and the best texture.

    Allow the brownies to cool completely in the pan at room temperature, about 2 hours. Then refrigerate for at least 3 hours, preferably overnight, to fully set.

12. Step 12: Dip your knife in hot water and wipe dry between cuts for professional-looking brownies.

    Once chilled, use the parchment paper overhang to lift the brownies out of the pan. With a sharp knife, cut into 16 squares, wiping the knife clean between cuts for the cleanest edges.

13. Step 13: These brownies actually taste better on the second day as the flavors meld together.

    Garnish with fresh raspberries if desired. Store leftover brownies in an airtight container in the refrigerator for up to 5 days.

For the best flavor and texture, allow these brownies to chill overnight before serving. They can be made up to 2 days in advance for special occasions. If you prefer a more intense raspberry flavor, you can add 1/4 teaspoon of raspberry extract to the cheesecake layer.