Chocolate Sheet Cake - Rise and Bake with Julie

Prep Time:20

Cook Time:35

Cooling Time:1

Total Time:1 55

Servings: squares

Author: Julie Gavin

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Ingredients

Cake Ingredients

2 c. (250 g) unbleached all-purpose flour (RECOMMEND WEIGHING)
2 c. (400 g) granulated sugar
1 tsp baking soda
½ tsp. salt
½ c. (113 g) salted butter
½ c. (110 g) avocado oil (or neutral oil)
1 c. (240 g) water
¼ c. (25 g) unsweetened cocoa powder
½ tsp. espresso powder optional
2 large eggs
⅔ c. (160 g) buttermilk

Frosting Ingredients

⅓ c. (80 g) milk
1½ c. (300 g) granulated sugar
5 tbsp. (70 g) salted butter, softened
¾ c. (130 g) semisweet chocolate chips

Instructions

Preheat oven to 325°F (165°C). Grease a 15×10-inch jelly roll pan thoroughly (butter or nonstick spray). Optional: line the bottom with parchment.
Sift the flour through a fine-mesh sieve into a large bowl. Add the sugar, baking soda, and salt. Whisk 20–30 seconds to aerate and combine. Set aside.
In a medium saucepan over medium-low heat, melt the butter. Add the avocado oil, water, cocoa powder, and espresso powder (if using). Stir constantly until smooth and just steaming (2–3 minutes; do not boil). Remove from heat and cool slightly.
In a separate bowl, whisk the eggs and buttermilk until smooth. To temper, slowly pour the warm cocoa mixture to the egg blend while whisking vigorously.
Pour the wet mixture into the dry ingredients and whisk until smooth and no dry pockets remain. The batter will be thin and pourable. Pour into the prepared pan.
Bake 30–36 minutes (check at 30 minutes). A toothpick inserted in the center should come out clean or with moist crumbs. Cool completely in the pan (~1 hour).
In a medium saucepan, combine milk, sugar, and butter. Bring to a boil over medium heat, stirring constantly. Boil for 30 seconds, then remove from heat. Stir in chocolate chips until fully melted and smooth.
Immediately pour the warm frosting over the cooled cake. Spread quickly and evenly for a glossy finish (work within 1–2 minutes before it sets).
Let frosting set (~30 minutes), then cut into squares. Store airtight at room temperature for up to 2–3 days or freeze for 3 to 4 months.

Notes

Avocado oil helps maintain moisture for days while the butter adds richness.
Sift flour to prevent clumps.