butterscotch mochi bars


  • for the butterscotch sauce (from Smitten Kitchen):
  • ¼ cup unsalted butter
  • ½ cup brown sugar
  • ½ cup heavy cream
  • ½ teaspoon kosher salt (or more, to taste)
  • 1 to 1 ½ teaspoon vanilla extract
  • for the cake:
  • 1½ cups (225 grams) sweet rice flour, like Mochiko Blue Star
  • 1 cup whole milk
  • ¾ cup sugar
  • ½ cup vegetable oil or other neutral oil
  • 2 large eggs
  • 1 teaspoon vanilla extract
  • Flaky sea salt, for topping


  1. Preheat the oven to 350°F and line a Pyrex 8-inch square baking dish with parchment paper.
  2. To make the butterscotch sauce: Melt the butter in a medium heavy-bottomed saucepan over medium heat. Add the sugar, cream and salt and whisk until well blended. Bring to a very gentle boil and cook for about five minutes, whisking occasionally.
  3. Remove from heat and stir in one teaspoon of the vanilla extract. Carefully taste a bit of the cooled sauce and adjust with more vanilla extract and salt to your liking. Set aside while you make the cake.
  4. To make the cake: In a medium Pyrex mixing bowl, combine the sweet rice flour, milk, sugar, oil, eggs, and vanilla, and whisk until smooth. You don’t need to worry about overworking the batter and making the cake dense, because sweet rice flour doesn’t contain gluten—mochi cake is dense to begin with! Small lumps will appear in the batter at first, but they will dissipate as you whisk.
  5. Pour half the batter into the prepared Pyrex baking dish. Drop small spoonfuls of the butterscotch sauce evenly across the batter, then pour the remaining batter over top. Drop small spoonfuls across the top and use a butter knife to swirl the sauce evenly throughout the cake. (You will have a good amount of butterscotch leftover. Given how good it is, I suspect you will forgive me.)
  6. Bake, uncovered, for 40 to 50 minutes, or until the edges are puffed and the center is set. Enjoy warm or at room temperature. The mochi will slice much more cleanly when cooled, but there’s nothing like enjoying a piece warm from the oven.


Some variations! Throw in a two-inch sprig of rosemary with the butter to make a rosemary butterscotch (and just remove the rosemary from the sauce after it simmers). Add in ½ teaspoon ground ginger, ½ teaspoon cinnamon, ¼ teaspoon ground cloves, ¼ teaspoon all spice, and a pinch black pepper for a gingerbread twist.

I find that this butterscotch version is best enjoyed the day that it’s baked, but other versions with red bean, black sesame, peanut butter, and chocolate will keep for at least two days in the Pyrex dish at room temperature, and longer in the fridge (though you’ll want to heat it briefly before serving).