Preheat the oven to 350°F (175°C).
Prepare a 9x13 inch baking pan by greasing it or lining with parchment paper.
Melt the butter in a medium saucepan over low heat.
Remove from heat and stir in granulated and brown sugar until fully combined.
Add eggs and vanilla extract, mixing until fully incorporated.
Sift in cocoa powder and flour, mixing until just combined.
Fold in fresh raspberries gently to avoid breaking them.
Pour the batter into the prepared baking pan and spread evenly.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted comes out mostly clean.
Allow brownies to cool in the pan for at least 15 minutes before cutting.