Whisk both black and Dutch-process cocoa powders with hot water before adding to batter to intensify chocolate flavor and eliminate any grittiness for a silkier crumb.

Bring eggs to room temperature before mixing to ensure proper emulsification with the oil and butter, resulting in a more tender, moist cake structure.

Pass your raspberry preserves through a fine-mesh sieve to remove seeds, creating a smooth, spreadable filling that won't interfere with the buttercream's silky texture.

Slowly pour melted dark chocolate into room-temperature butter while whisking to prevent seizing; the buttercream should be around 70°F for that perfect silk-like consistency that's sturdy enough for three layers.

Refrigerate each cooled cake layer for at least 2 hours before stacking to prevent shifting and ensure the preserves and buttercream set properly for clean, professional-looking slices.