Preheat oven to 350 degree F. Butter and flour a 9-inch round cake pan or spring form pan.
In a large bowl, mix the cocoa and sugar.
Melt butter and jam in a saucepan over low heat, pour over sugar and cocoa mixture and stir until well combined.
After cooling about 5 minutes, add one egg at a time to the mixture and blend until smooth and satiny.
Add flour, salt and vanilla and blend until combined.
Pour batter into prepared pan and smooth top with a spatula.
Bake for 15 minutes. Reduce heat to 325 degrees F and continue baking for another 45 minutes or until toothpick inserted in the center comes out with moist crumbs.
Allow to cool in the pan for 1 hour. Cut around the edges and then turn out onto a plate. This cake tends to be very moist and fudgy in the middle. (If it is difficult to get the cake out of the pan, run the bottom of the pan over a stove burner for several seconds).
Let sit another hour, out of the pan, and it will slightly firm up and be easier to cut. Warm the extra jam and brush on the cake. Top with fresh raspberries, dust with confectioner's sugar and enjoy!