Easy Peanut Butter Sheet Cake Recipe

My First Peanut Butter Cake

I made this cake for my grandson’s birthday. He loved peanut butter more than anything. His face lit up when he saw it. I still laugh at that.

This cake is pure joy on a plate. It is not fancy. It is home. That is why it matters. It turns a simple day into a sweet memory. What is your favorite birthday treat from childhood?

Why This Recipe Works

The cake is wonderfully moist. The oil and buttermilk see to that. The glaze is where the magic happens. It soaks into the warm cake just a little.

You get a soft cake with a gooey, peanut-buttery top. Fun fact: The marshmallows in the glaze melt completely. They make it silky smooth! Does your family prefer smooth or chunky peanut butter for baking?

A Little Kitchen Secret

Do not over-mix the batter. Just whisk until everything is combined. A few small lumps are just fine. They will bake out, I promise.

This matters because gentle mixing keeps the cake tender. A tough cake is a sad cake. Pour that glaze on while the cake is still warm. Doesn’t that smell amazing? It makes the whole kitchen feel cozy.

More Than Just a Dessert

This is a sharing cake. You bake it in a big sheet pan. It is meant for a crowd, for a school event, or for neighbors. Food is how we say, “I’m glad you’re here.”

That is the second reason this recipe matters. It builds community. It is an easy way to show you care. What was the last thing you baked to share with others?

Let’s Get Baking

Gather your ingredients. Grease that pan well. The most important step is the first bite. Make sure you get a corner piece with extra glaze.

Trust your nose near the end of baking. If it smells like toasted peanuts, it is likely done. Always do the toothpick test. Then, let the happy eating begin.

Ingredients:

Ingredient	Amount	Notes
all-purpose flour	2 cups
sugar	2 cups
baking soda	1 teaspoon
salt	1/2 teaspoon
water	1 cup
butter, cubed	3/4 cup
chunky peanut butter	1/2 cup
canola oil	1/4 cup
large eggs, room temperature	2
buttermilk	1/2 cup
vanilla extract	1 teaspoon
Glaze:
sugar	2/3 cup
evaporated milk	1/3 cup
butter	1 tablespoon
chunky peanut butter	1/3 cup
miniature marshmallows	1/3 cup
vanilla extract	1/2 teaspoon

My Easy Peanut Butter Sheet Cake

Hello, my dear! Come sit at the counter. Let’s bake my famous peanut butter cake. It’s so simple and always brings smiles. I think of my grandson, Tommy, every time I make it. He once ate two pieces before dinner! I still laugh at that. This cake is soft, sweet, and full of peanut butter goodness. Doesn’t that smell amazing? Let’s begin our little baking story together.

Step 1: First, turn your oven to 350°. Grease your big, flat baking pan well. Now, mix the flour, sugar, baking soda, and salt in a big bowl. In a saucepan, put the water and butter cubes. Heat it until it just starts to bubble. Then stir in the peanut butter and oil. It will become a smooth, wonderful mess. (A hard-learned tip: measure your flour by spooning it into the cup. Don’t scoop! This keeps the cake light.)

Step 2: Pour that warm peanut butter mix into your flour bowl. Stir it all together. It will look thick. Now, in a smaller bowl, whisk the eggs, buttermilk, and vanilla. Add this to your big bowl. Whisk everything until it’s just combined and smooth. See how the batter shines? That’s the promise of a tender cake. Do you like chunky or smooth peanut butter better? Share below!

Step 3: Pour your batter into that greased pan. Spread it gently to the corners. Slide the pan into your hot oven. Bake it for 20 to 25 minutes. You’ll know it’s done when a toothpick poked in the middle comes out clean. Your kitchen will smell like a dream. Let the cake rest while you make the magic glaze.

Step 4: For the glaze, combine sugar, evaporated milk, and butter in a clean pan. Bring it to a boil, stirring the whole time. Let it bubble for two full minutes. Then take it off the heat. Quickly stir in the peanut butter, marshmallows, and vanilla. The marshmallows will melt into sweet, sticky joy. Spoon this warm glaze all over your warm cake. Spread it to the edges. Let the whole thing cool. The waiting is the hardest part!

Cook Time: 25 minutes
Total Time: 45 minutes
Yield: 24 pieces
Category: Dessert, Cake

Three Fun Twists to Try

This cake is a perfect friend for your own ideas. Feel like playing? Here are three twists I love. Chocolate Swirl: Drop spoonfuls of chocolate syrup on the batter before baking. Swirl with a knife. Banana Party: Add one mashed ripe banana to the batter. It tastes like a peanut butter sandwich! Salty-Sweet Crunch: Sprinkle crushed pretzels on top of the wet glaze. Which one would you try first? Comment below!

Serving It Up Just Right

This cake is wonderful all on its own. But for a special touch, serve it slightly warm. A little scoop of vanilla ice cream on the side melts beautifully. For a pretty plate, add a few banana slices and a drizzle of honey. To drink, a cold glass of milk is the classic choice. For the grown-ups, a cup of strong coffee pairs wonderfully with the sweet peanut butter. Which would you choose tonight?

Keeping Your Peanut Butter Cake Perfect

This cake stays wonderfully moist. Just cover the pan tightly. It will be good on the counter for two days. For longer, pop it in the fridge for up to five days.

You can freeze it, too. I cut the cooled cake into pieces. I wrap each piece in plastic wrap. Then I put them all in a freezer bag. I once forgot a piece in the back for a month. It tasted just fine thawed!

Batch cooking this is a smart move. It saves you time later. You can have a sweet treat ready anytime. This matters because life gets busy. A homemade dessert should make life easier, not harder.

Have you ever tried storing it this way? Share below!

Simple Fixes for Common Cake Troubles

Is your cake too dry? You might have baked it too long. Check it at 20 minutes with a toothpick. I remember when my first one was like a brick. I learned to watch the clock closely.

Is the glaze too thick or thin? If thick, add a splash more evaporated milk. If thin, let it cool a bit more. It will thicken as it sits. Getting the glaze right matters. It makes the cake look and taste special.

Did the cake sink in the middle? Your baking soda might be old. Test it with a little vinegar. If it doesn’t bubble, get a new box. Fixing little issues builds your confidence. You learn something new every time you bake.

Which of these problems have you run into before?

Your Quick Questions, Answered

Q: Can I make this gluten-free?
A: Yes! Use your favorite gluten-free flour blend. The results are just as tasty.

Q: Can I make it ahead?
A: Absolutely. Bake the cake a day early. Add the glaze just before serving.

Q: What if I don’t have buttermilk?
A: No problem. Put one tablespoon of vinegar in a cup. Fill the rest with milk and let it sit for 5 minutes.

Q: Can I double the recipe?
A: You can, but bake it in two pans. One pan will be too full and may not bake evenly.

Q: Any optional tips?
A: Try a sprinkle of sea salt on the glaze. Fun fact: A little salt makes sweet things taste even sweeter.

Which tip will you try first?

From My Kitchen to Yours

I hope you love this cake as much as I do. It always reminds me of my grandkids after school. Their happy faces are the best reward.

I would love to see your creation. Sharing food connects us all. It is my favorite part of writing these recipes.

Have you tried this recipe? Tag us on Pinterest! Use @ChloesCozyKitchen so I can find your photos. Happy cooking!

—Chloe Hartwell.