Preheat your oven to 180°C (350°F). Line a cake tin or muffin cups with parchment paper.
In a large bowl, whisk the egg, soy milk, and sweetener until well combined.
Add the rice flour, kinako, and baking powder to the bowl. Mix well until the batter is smooth.
Add the steamed chestnuts to the batter. Fold them in gently so they are evenly distributed without breaking them too much.
Pour the batter into the tin. Bake at 180°C for about 30 minutes.(Tip: Insert a toothpick into the center; if it comes out clean, it’s done!)
