Preheat oven to 350°F (175°C). Lightly grease and line a 9x13-inch sheet cake pan with parchment paper leaving a small overhang for easy removal. Set aside.

In a large bowl, whisk together the all-purpose flour, granulated sugar, unsweetened cocoa powder, baking powder, baking soda, and fine salt until evenly combined and no lumps of cocoa remain.

In a separate medium bowl or large measuring cup, beat the eggs lightly, then add the whole milk, neutral oil, hot coffee, and vanilla extract. Stir until homogeneous. The hot coffee should be warm but not boiling (about 130–140°F / 55–60°C) to help bloom the cocoa.

Pour the wet ingredients into the dry ingredients and fold gently with a rubber spatula or whisk just until combined. Scrape the bottom and sides of the bowl. Do not overmix — a few small streaks are okay.

Pour the batter into the prepared 9x13 pan and smooth the top with an offset spatula or the back of a spoon so the surface is even.

Bake in the center of the preheated oven for 20–26 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs (not wet batter). Baking time will vary by oven and pan; start checking at 18 minutes.

Remove the cake from the oven and place on a wire rack. Let cool in the pan for 15 minutes, then use the parchment overhang to lift the cake out and transfer to the wire rack to cool completely (about 45–60 minutes). Cooling completely is important so the topping stays light and doesn’t melt.

Whipped Chocolate Cloud Topping

Chill a large mixing bowl and beaters (or a stand mixer bowl and whisk) in the refrigerator for at least 10 minutes prior to whipping for best volume.

In the chilled bowl, beat the softened cream cheese briefly until smooth and free of lumps (about 30 seconds) on medium speed.

Add the cold heavy cream, powdered sugar, unsweetened cocoa powder, espresso powder (if using), vanilla extract, and fine salt to the bowl with the cream cheese.

Start whipping on low speed to incorporate ingredients, then increase to medium-high. Whip until medium-firm peaks form and the mixture is airy and spreadable — about 3–5 minutes depending on your mixer. Be careful not to overbeat; the mixture should hold peaks but remain cloud-like and light.

Taste and adjust sweetness or cocoa intensity: add up to 2 tablespoons more powdered sugar for sweeter topping or 1–2 teaspoons more cocoa powder for a deeper chocolate flavor, then briefly whisk to incorporate.

Once the cake is completely cooled, transfer it to a serving platter or keep it in the pan. Gently spread the whipped chocolate cloud topping over the cake with an offset spatula, creating soft swirls and peaks to evoke a 'cloud' appearance. Work quickly but gently to keep the topping airy.

Garnish and Serve

If using, sprinkle chocolate shavings or curls across the top, scatter fresh raspberries or berries over sections of the cake, and finish with a light sprinkle of sea salt flakes to enhance the chocolate flavors.

For best texture, chill the assembled cake for 20–30 minutes to slightly set the topping, or serve immediately. Store leftover cake covered in the refrigerator for up to 3 days. Allow refrigerated slices to sit at room temperature for 10–15 minutes before serving for the best mouthfeel.