Follow these simple steps to create the Best Raspberry Swirl Brownies:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease a 9×13 inch baking pan or line it with parchment paper for easy removal.
2. Melt the Butter: In a medium saucepan, melt the unsalted butter over low heat. Once melted, remove from heat and let it cool slightly.
3. Combine Sugar and Eggs: In a large mixing bowl, combine the granulated sugar and eggs. Whisk until the mixture is smooth and creamy.
4. Add Vanilla: Stir in the vanilla extract.
5. Incorporate Butter: Gradually add the melted butter to the egg mixture, mixing until well combined.
6. Mix Dry Ingredients: In another bowl, sift together the flour, cocoa powder, and salt. Gradually fold the dry ingredients into the wet mixture until just combined. Be careful not to overmix.
7. Prepare Raspberry Swirl: In a small bowl, mash the fresh raspberries with a fork. If desired, mix in the raspberry jam for added sweetness and a smoother texture.
8. Layer the Batter: Pour half of the brownie batter into the prepared baking pan. Spread it evenly across the bottom.
9. Add Raspberry Mixture: Dollop spoonfuls of the raspberry mixture over the brownie batter. Use a knife or a toothpick to gently swirl the raspberry into the batter.
10. Add Remaining Batter: Pour the remaining brownie batter over the raspberry swirl. Again, use a knife to create a marbled effect by swirling it lightly.
11. Bake: Place the pan in the preheated oven and bake for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
12. Cool: Remove the brownies from the oven and allow them to cool in the pan for about 20 minutes. Then, transfer them to a wire rack to cool completely before cutting.

These steps will guide you in creating the Best Raspberry Swirl Brownies that are both delicious and visually appealing.