The BEST Chocolate Sheet Cake Recipe

TL;DR

A foolproof chocolate sheet cake using Dutch-processed cocoa, hot coffee, and oil for a fudgy, soft texture with silky chocolate buttercream.

Key Points

• 1.Dutch-processed cocoa is key for fudginess. Use 50g (½ cup) — it's darker, less acidic, and produces a richer, fudgier bake than regular cocoa powder.
• 2.Hot coffee (1½ cups) blooms the cocoa for deeper chocolate flavor. You won't taste coffee — it simply intensifies the chocolate; boiling water works as a substitute.
• 3.Oil over butter keeps the cake soft in the fridge. Butter firms up when chilled; vegetable oil (¾ cup) stays tender, though a 50/50 split is also an option.
• 4.Buttermilk (1 cup) and sour cream (½ cup) tenderize the crumb. Both are acidic, which inhibits gluten development and reacts with baking soda for a lighter texture.
• 5.Sugar does more than sweeten — it softens. Reducing the 530g of granulated sugar will make the cake less sweet but noticeably firmer and more bread-like.
• 6.The buttercream gets upgraded with hot fudge. Adding ⅓ cup (100g) of hot fudge to the cocoa-butter frosting makes it more intense, chocolatey, and silky than cocoa alone.