Prep. Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners. Set aside.
Mix dry ingredients. Whisk together ube mochi pancake mix, sugar, baking powder, and salt in a large bowl.
Combine wet ingredients. In a separate bowl, whisk coconut milk, grapeseed oil, eggs, and ube extract until smooth and emulsified.
Wet and dry. Pour wet ingredients into dry ingredients. Stir together until smooth. Don't worry about over-mixing since this batter does not contain flour.
Portion. Divide batter evenly among prepared cups, filling each about ⅔ full.
Bake. Bake 18-20 minutes until tops spring back when lightly pressed and a toothpick inserted in the center comes out clean or with a few moist crumbs.
Cool. Let cupcakes cool in the pan 5 minutes, then transfer to a wire rack. Cool fully before frosting.
Frosting:
Stir the ube halaya in a large bowl until it reaches a smooth, spreadable consistency similar to peanut butter or mayonnaise. If it's too thick or stiff, add 1 tablespoon of canned coconut milk to thin it out.
Add butter and cream cheese to ube halaya. Beat together until smooth. Scrape down sides of bowl as needed to ensure thorough mixing.
Add ube extract and confectioners' sugar. Beat on low speed until sugar is incorporated. Increase to medium-high speed and beat for about 2 minutes until frosting is smooth and silky.
Notes
Storage: Store frosted cupcakes in an airtight container for up to 24 hours. After that time, keep frosted cupcakes in the fridge in an airtight container for up three additional days. Bring to room temperature before serving for best texture and flavor.