This Samoa sheet cake has the chocolate-caramel-coconut flavor people love in a cookie, but it bakes as one practical 9×13-inch cake. The thin chocolate layer, toasted coconut, glossy caramel, and dark chocolate drizzle give every square a clear contrast of textures.
Recipe at a glance: Prep 25 minutes – Bake 25-28 minutes – Cool and set 70 minutes – Yield 24 squares – Pan 9×13-inch metal baking pan – Oven 350F
Ingredients
Chocolate sheet cake
- 2 cups all-purpose flour
- 3/4 cup unsweetened cocoa powder
- 1 1/2 cups granulated sugar
- 1 teaspoon baking soda
- 1/2 teaspoon fine salt
- 2 large eggs
- 1 cup buttermilk
- 1/2 cup neutral oil
- 2 teaspoons vanilla extract
- 1 cup hot coffee
Caramel coconut topping
- 1 (11-ounce) jar caramel sauce
- 2 cups unsweetened shredded coconut, toasted and cooled
- 4 ounces semisweet chocolate, melted
- 1 tablespoon coconut oil
How to Make Samoa Sheet Cake
1. Prepare the pan and batter
Heat the oven to 350F. Grease a 9×13-inch light metal pan, line it with parchment, and leave two paper handles. Whisk the flour, cocoa, sugar, baking soda, and salt in a large bowl. Add the eggs, buttermilk, oil, and vanilla. Whisk just until smooth, then slowly whisk in the hot coffee. The batter will be thin; that is what keeps this sheet cake tender.
2. Bake and cool
Pour the batter into the pan and bake for 25 to 28 minutes. The center is ready when it springs back lightly and a toothpick comes out with a few moist crumbs. Cool in the pan for 20 minutes, then lift the cake onto a rack and cool completely before topping.
3. Add caramel and coconut
Toast the coconut in a dry skillet over medium-low heat for 4 to 6 minutes, stirring often, then cool it. Warm the caramel sauce for 15 to 20 seconds so it spreads easily; do not make it hot. Stir in the toasted coconut and spread the mixture over the fully cooled cake, reaching the corners without pressing into the crumb.
4. Drizzle and set
Melt the semisweet chocolate with the coconut oil in short 15-second bursts, stirring between each burst. Drizzle in thin lines over the caramel coconut layer. Chill the pan for 60 minutes, or until the topping is firm enough to cut cleanly.
Cutting, Storage, and Make-Ahead Tips
Use the parchment handles to transfer the cake to a board. For 24 neat squares, cut the 9×13 cake into 6 columns and 4 rows; wipe the knife between cuts. Store covered in the refrigerator for up to 5 days. Let squares sit at room temperature for 10 minutes before serving so the caramel softens. Freeze individually wrapped squares for up to 2 months and thaw overnight in the refrigerator.
Common Mistakes to Avoid
- Using a small pan: an 8×8 pan makes the cake too thick and changes the bake time.
- Spreading topping on warm cake: warm cake makes caramel slide and turn greasy.
- Skipping toasted coconut: toasting adds the nutty flavor that makes the Samoa profile recognizable.
- Overheating chocolate: short bursts keep the drizzle fluid and glossy.
Frequently Asked Questions
Can I use milk instead of buttermilk?
Use 1 cup milk plus 1 tablespoon lemon juice. Rest it for 5 minutes before adding; the acidity helps the baking soda lift the cake.
Can I make it ahead?
Yes. Bake the cake one day ahead, cool it, wrap it, and add the topping the next day. Chill after topping before slicing.
Should I use sweetened coconut?
Unsweetened coconut keeps the caramel balanced. Sweetened coconut works in a pinch, but the finished squares will be noticeably sweeter.
Final Thoughts
This version is written to be repeatable: the pan size, measured ingredients, temperature, timing, setting time, yield, and storage guidance all match the rectangular visuals. Save it for bake sales, potlucks, or any time a chocolate-coconut dessert needs to travel well.