Preheat oven to 350°F (180°C). Lightly grease 2 8" round cake pans or spring-form pans. Line the bottom with parchment paper and grease again.
In a small mixing bowl, sift together flour, cocoa powder, baking soda, baking powder and salt.
In a large mixing bowl, combine milk, oil, jam, vanilla and the sugar. Mix it well with a whisk. The jam should be mostly dissolved with the rest of the ingredients; some small lumps are fine.
Add the dry ingredients to the wet ingredients in batches and mix until everything is incorporated and there are no lumps.
Divide the batter between the 2 prepared pans* and bake for 30~35 minutes, or until a toothpick or a cake tester inserted in the center of the cake comes out clean.
Remove from the pan and let cool in pans for 10-15 mins, then run a knife around the cake and remove onto a wire rack. Cool completely before frosting.