Preheat your oven to 350F and grease an 9x13 baking dish.
In a large bowl, whisk together your butter, sugar, eggs, evaporated milk, coconut milk, ube extract, and vanilla extract until well combined.
Next, add in your mochiko flour and baking powder and whisk until the batter is smooth.
Pour into baking dish in an even layer and bake in oven for 1 hour.
After 1 hour, let cool for 30 minutes then enjoy!