This Pistachio-Chocolate Snacking Cake is the kind of dessert you bake when you want something deeply chocolatey, ultra-moist, and easy—but still special enough to feel “bakery level.” The cake uses Dutch-process cocoa bloomed in boiling water to intensify the chocolate flavor, and buttermilk to keep it tender with a subtle tang.

Below is a complete, step-by-step recipe based on Food & Wine’s version, written in my own words, plus helpful tips and an easy variation option.

Quick Recipe Details

• Yield: 1 (8-inch square) cake
• Active time: ~40 minutes | Total time: ~2 hours 25 minutes
• Pan: 8-inch square pan
• Oven: 350°F / 175°C

Ingredients

For the Chocolate Cake

• Cooking spray
• 1/2 cup boiling water
• 1/2 cup Dutch-process cocoa powder
• 1 cup packed light brown sugar
• 1/4 cup vegetable oil
• 2 teaspoons vanilla extract
• 1 large egg + 1 egg yolk
• 1/2 cup whole buttermilk
• 3/4 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1/2 teaspoon kosher salt
• 1 cup all-purpose flour

For the Pistachio Frosting

• 1/2 cup unsalted butter, softened
• 1 1/2 teaspoons vanilla extract
• 1/2 teaspoon kosher salt
• 1 1/2 cups powdered sugar
• 1/2 cup pistachio paste
• 2 tablespoons heavy cream
• 2 to 4 drops green food coloring (optional)
• Chopped pistachios (for garnish)

Step-by-Step Instructions

1) Prep the pan and oven

1. Heat your oven to 350°F / 175°C.
2. Lightly coat an 8-inch square baking pan with cooking spray.
3. Line the pan with parchment so it covers the bottom and sides, leaving an overhang on two opposite sides (this makes lifting the cake out easy).

2) Bloom the cocoa (for deeper chocolate flavor)

1. In a small heatproof bowl, whisk boiling water and Dutch-process cocoa until smooth.
2. Set aside while you mix the rest of the batter.

3) Mix the cake batter (one-bowl style)

1. In a large bowl, whisk together the brown sugar, oil, and vanilla until glossy and well blended.
2. Whisk in the whole egg, then the egg yolk, then the buttermilk until smooth.
3. Sprinkle in baking powder, baking soda, and salt; whisk to combine.
4. Pour the cocoa mixture on top (don’t worry about mixing it first). Add the flour, then whisk firmly until the batter looks uniform—just until combined (avoid overmixing).

4) Bake

1. Scrape the batter into the prepared pan and smooth the top.
2. Bake for about 25 minutes, turning the pan halfway through, until a toothpick comes out with a few moist crumbs (not wet batter).
3. Cool completely in the pan on a rack—about 1 hour 30 minutes.
4. Lift the cake out using the parchment “handles,” then move it to a platter and peel off the parchment.

5) Make the pistachio frosting

1. In a stand mixer (paddle attachment), beat softened butter, vanilla, and salt until smooth (about 1 minute).
2. On medium-low speed, gradually beat in powdered sugar, then pistachio paste, then heavy cream, scraping the bowl as needed.
3. If you want a brighter green, add 2–4 drops of green food coloring.
4. Increase speed to medium-high and beat until the frosting is lighter and fluffy (about 2 minutes).

6) Frost and finish

1. Spread the pistachio frosting over the cooled cake.
2. Sprinkle with chopped pistachios.
3. Slice into squares and serve.

Notes, Tips, and Easy Variations

Why this cake stays so moist

Food & Wine highlights two key tricks: oil helps keep the crumb tender and moist longer than butter-only cakes, and blooming cocoa in hot water boosts chocolate intensity.

No pistachio paste?

You can make a chocolate frosting instead: swap the pistachio paste for 1/4 cup Dutch-process cocoa, skip the food coloring, and finish with chocolate curls if you like.

Storage

Food & Wine notes the frosted cake keeps well at room temperature in an airtight container for up to 2 days.
(Other bakers commonly refrigerate frosted snack cakes longer; for example, a similar pistachio-chocolate snack cake keeps 4–5 days in the fridge and can be frozen in squares.