Raspberry Butter Mochi (and Cake Scaling 101!)

Have you ever had butter mochi? I went the first 30 years of my life without it, sadly, until my first visit to Hawaii. It was a warm Pacific morning and we were driving down the highway when suddenly my boyfriend spotted a roadside mochi stand on the other side of the road. Screeching to a halt and nearly causing an accident in Honolulu traffic, he promptly did a u-turn. But it was worth it. That was the day I first tasted the perfection that is butter mochi: a rich gooey cake, crispy on the outside but soft and chewy in the middle.

Mochi is Japanese in origin, a cake made out of glutinous rice that has been processed into a flour. You’re most likely to find it in an Asian grocery store (I found it at Katagiri) and Mochiko is the most common brand. When you hear the word mochi you may think first of ice cream – this use of the mochi cake has become the most common in the US. Butter mochi is different – a Hawaiian dessert that mixes glutinous rice flour with alarming amounts of butter and sugar to produce rich, bite-sized cakes.

Returning to the mainland I dreamed of butter mochi (and the view above of course). I spent my time rabidly followed Da Mochi Guys, the vendor, on Instagram, waiting for my Hawaii return until I saw this Raspberry-Mochi Butter Cake with Matcha Glaze in NY Times Cooking. I knew I had to make it; it looked too good to be true. There was just one problem – the recipe called for a 9-inch round cake pan, and I have a 9-inch square cake pan. Same difference, right? In the past I would have cooked the recipe as normal, ignoring the difference in pans, but since launching this blog I’ve been learning as much about cooking as I can, so I looked it up.

And no, it’s not a good idea to cook the same amount of batter in a 9-inch round and a 9-inch square cake pan because circles and squares don’t have the same area (duh). You’ll end up with a cake that’s too thick, too thin, burnt, or undercooked. Enter high school math – you can easily adapt a cake recipe for any size or shape pan. You only need to find the change in area of the two pans, then scale accordingly. The trick is to only scale by area – you might be tempted to scale by volume, because cakes have height too, but unless you want a cake that’s 20% thicker than what you intended (you don’t), you’ll want to scale by area.

That’s a lot of math to remember, so I’ve used my day-job Excel skills to create this handy conversion tool:

All you have to do is type in your pan dimensions and the original recipe, and it will scale it automatically. I used it to scale the butter mochi for my square pan, and it worked perfectly. But it is built to scale from any size, ranging from giant sheet cake to tiny ramekin. You’re welcome.

The recipe was out-of-this world incredible, so good that I couldn’t believe I had made it at home. I would change nothing, except for scaling the recipe to fit your pan. Show off at your next party or just enjoy at home; either way prepare yourself for decadence.

Raspberry Butter Mochi Cake with Matcha Glaze

Yields one 9″ square cake; 80 minutes plus cooling time


Butter Mochi Cake

  • 70 grams butter unsalted, melted
  • 400 grams glutinous rice flour (Mochiko)
  • 462 grams granulated sugar
  • 2 1/2 teaspoons baking powder
  • 228 milliliters full-fat coconut milk
  • 228 milliliters evaporated milk
  • 2 1/2 eggs*
  • 1 tablespoon + 1 teaspoon vanilla extract
  • 15 ounces fresh raspberries

*To get half an egg, break the yolk in a small bowl and whisk until the yolk is just dissolved. Weight the egg mixture and put half the weight into your batter.

Matcha Glaze

  • 355 grams confectioner’s sugar
  • 100 milliliters full-fat coconut milk
  • 2 1/2 teaspoons matcha powder


  • 9″ square baking pan
  • Parchment paper
  • Large bowl
  • Whisk


  1. Heat oven to 350 degrees F. Line the bottom of your baking pan with parchment paper. Grease the sides and bottom of the pan with butter.
  2. In a large bowl, whisk together flour, sugar, and baking powder. In a medium bowl, whisk together coconut milk, evaporated milk, eggs, vanilla, and melted butter. Pour the wet ingredients into the dry ingredients and whisk thoroughly until combined.
  3. Pour batter into baking pan. Add raspberries to cake batter one by one, approximately 1″ apart. Press down slowly until submerged in batter. You will have leftover raspberries to top your cake.
  4. Bake the cake until the top is golden brown and the center comes out clean when a toothpick is inserted, approximately 60 minutes.
  5. Remove from heat and let sit for 10 minutes. Then run a knife around the inside of the pan. When it’s cool enough to handle, invert it onto a serving platter and let it cool completely.
  6. Make the matcha glaze by whisking together confectioner’s sugar, coconut milk, and match powder. Whisk until smooth and set aside.
  7. Once cake has cooled completely, spoon a small amount of matcha glaze on the cake. Using the back of a spoon, spread the glaze over the top and let it drip down the sides. Continue to add glaze as needed, being careful not to overly glaze it (you will have leftover glaze).
  8. Place the remaining raspberries in a pile in the center of the cake. Dust the cake with confectioner’s sugar and serve immediately.

6 Comments Add yours

  1. Into Realm says:

    I have never tried matcha. I feel it is some kind of powder? It is not that


    1. Matcha is green tea leaves that have been ground into a powder. It can be used to make tea or to flavor foods…in my opinion it is a strong green tea/earthy flavor!


      1. Into Realm says:

        Oh… i never knew..
        Well, then it makes sense in the types of recipes it is used. Thankyou so much


      2. You’re welcome!


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