Ooey Gooey Chocolate Insanity Cake

I’m sharing my take on a decadently rich, ultra-moist chocolate sheet cake with a fudgy, hot chocolate icing poured right over the still-warm cake—a gooey, chocolate-lover’s dream that's easy to whip up in just 30 minutes.

Why You’ll Love This Recipe

I love how quick and fuss-free this cake is—done in just half an hour! The contrast between the warm, gooey cake and the hot fudge icing creates an irresistible texture. I also adore how it’s made in a single 9×13 pan, giving plenty to share (or keep all to myself).

Ingredients

(Here's a tip: Check out the full list of ingredients and measurements in the recipe card below.)

For the cake

• 2 cups sugar

• 2 cups all-purpose flour + 1 tablespoon for chocolate chips

• 1 teaspoon baking powder

• 2 teaspoon baking soda, divided

• ½ lb unsalted butter

• ¼ cup sweetened cocoa powder

• 1 cup water

• 2 large eggs

• ½ teaspoon kosher salt

• ½ cup milk

• ½ tablespoon vinegar

• 1 teaspoon vanilla extract

• 1½ cups semi-sweet chocolate chips

For the icing

• ¼ cup sweetened cocoa powder

• ¼ lb unsalted butter

• 6 tablespoon milk

• 1 lb powdered sugar

• 1 teaspoon vanilla extract

• ¼ teaspoon salt

Directions

1. Preheat oven to 375 °F and butter + flour a 9×13 pan.

2. In a small cup, combine milk and vinegar; set aside.

3. Whisk together flour, sugar, baking powder, 1 teaspoon baking soda, and salt.

4. In a saucepan, bring butter, cocoa, and water to a boil; pour into dry mixture and beat well.

5. Stir baking soda into the milk mixture; set aside.

6. Toss chocolate chips with 1 tablespoon flour.

7. Beat eggs into the cocoa–flour mixture, then stir in milk mixture and vanilla. Fold in chocolate chips.

8. Pour batter into the prepared pan; bake 20 minutes or until a toothpick comes out clean.

9. Five minutes before cake finishes, prepare icing: boil cocoa, butter, and milk, remove from heat, then beat in powdered sugar, salt, and vanilla.

10. Pour icing over the hot cake, spreading evenly. Serve warm.

Servings and timing

Makes 12 servings.

• Prep time: ~10 minutes

• Bake time: ~20 minutes

• Total time: ~30 minutes

Variations

• Swap vinegar + milk for ½ cup buttermilk for tangy richness.

• Use unsweetened cocoa if that's what’s on hand—flavor’s still great.

• Stir in chopped nuts or swirl in peanut butter under the icing.

• Add a shot of espresso or instant coffee to deepen the chocolate flavor.

• Skip the icing and dust with powdered sugar for a lighter touch.

Storage/Reheating

I store leftovers in the fridge, tightly wrapped, and it keeps well for up to 2 days. For freezing, I slice, flash-freeze them about an hour on a baking sheet, then wrap pieces in plastic and foil—good for up to 3 months. I thaw overnight in the fridge and warm in the microwave for a gooey treat.

FAQs

What makes this cake “insanity” level?

This cake earns its name because it combines intense chocolate flavor, a moist crumb, gooey melted chips, and a hot fudge-style icing—all in one quick bake. It’s delightfully over-the-top!

Can I use a different pan size?

Sure! A 9×13 works best, but I sometimes use two 8×8 pans—just watch baking time and test with a toothpick until it’s done.

Do I have to use the icing?

Nope! The cake is delicious on its own. I often skip the icing and just sift powdered sugar over the top for a simpler finish.

Can I make this gluten-free?

Yes—just swap the flour for a 1:1 gluten-free blend. The texture stays wonderfully moist.

How do I get the icing thick enough?

I let the icing cool a few minutes after mixing before spreading—this helps it thicken just enough to coat the cake without soaking in too thinly.

Conclusion

I love how this cake delivers maximum chocolate goodness with minimal effort. It's perfect for last-minute gatherings or indulgent weeknight desserts. The ooey-gooey texture and hot chocolate icing are pure comfort. Try it once, and I promise it'll become a go-to in my kitchen!