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Vegan Gluten-Free Vanilla Cake with Rainbow Frosting

Vegan Gluten-Free Vanilla Sheet Cake with Rainbow Frosting

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3.7 from 3 reviews

  • Author: Elaine Gordon
  • Total Time: 45 minutes
  • Yield: 16 1x
  • Diet: Vegan


This vegan and gluten-free vanilla sheet cake has a vibrant rainbow swirl frosting that makes it extra festive.  The cake is light, fluffy and perfectly sweet.  Best of all, this easy recipe contains nutritious ingredients that you can feel really good about.


  • 3 cups gluten-free old fashioned oats
  • 2 teaspoons baking powder
  • 1/2 teaspoon fine salt
  • 1 cup plain, unsweetened plant-based milk (I have tested with oat and almond milk)
  • 1/2 cup pure maple syrup
  • 1/2 cup avocado oil
  • 1 tablespoon vanilla extract
  • 2 batches of Vegan Vanilla Frosting (divided into seven tiny bowls for separate food coloring)


  1. Preheat oven to 350 degrees Fahrenheit. Lightly grease an 8 x 8 baking pan with avocado oil or coconut oil and set aside.
  2. In a high speed blender, add the oats and blend on the highest speed until a super fine oat flour forms. There should be no oat chunks remaining. Place the homemade oat flour into a mixing bowl.
  3. Add baking powder and salt and stir well to combine. Add milk, maple syrup, avocado oil and vanilla and stir again until well combined.
  4. Pour the cake batter into the greased baking pan and bake for 30 minutes.
  5. While the cake bakes, make a double batch of the vegan vanilla frosting.  Divide the frosting evenly into seven tiny bowls and add 8-10 drops of natural food coloring to each bowl.  Stir with a spoon to distribute the color evenly.  Store the frosting bowls in the refrigerator until ready to use.
  6. When the cake is finished baking allow it to fully cool before frosting it. I like to stick the entire pan in the freezer to speed up the process.  Once fully cooled, gently spread the colored frosting onto the cake in an even layer.  It is okay if the colors overlap slightly.  For this particular design, I start with red and then do orange, yellow, green, blue, purple and pink vertical lines.  Then I use a chopstick to make horizontal lines in the opposite direction (this makes the pattern you see in the pictures but you can swirl however you want - just don't over-swirl or the colors will combine to create brown).  Garnish your cake with dye-free sprinkles if desired. You can also garnish the cake with crushed freeze dried raspberries.
  7. Slice into 16 slices and enjoy.  Store leftovers in an airtight container in your refrigerator.  Allow the cake to come back to room temperature before enjoying.
  • Prep Time: 15
  • Cook Time: 30
  • Category: Dessert
  • Method: Oven Baked