Preheat oven to 180°C/350°F (all oven types). Line a 12-hole muffin tin with cupcake liners.

Canned pineapple: Drain crushed pineapple well, reserving the juice. Measure out 3/4 cup pineapple and 2 tbsp pineapple juice.

Whisk Dry Ingredients: Whisk Dry ingredients in a large bowl.

Whisk Wet Ingredients: In a separate bowl, whisk together the milk, vinegar, eggs, sugar, oil and the 2 tbsp pineapple juice from Step 2.

Add-ins: Stir in carrot, crushed pineapple, coconut and pecans into the Wet ingredients bowl.

Combine Wet & Dry: Pour Wet into Dry ingredients, stir only until flour is no longer visible. Batter will be lumpy (from the stir-ins) and thick, but runny.

Fill muffin tin: Divide batter between 12 holes. (A 3-tbsp levered ice cream scoop makes life super-easy here.)

Bake 20 minutes or until a toothpick inserted into the centre comes out clean. Transfer to cooling rack and fully cool before frosting.

Cream butter: Using the paddle attachment on a stand mixer (or whisk attachments for hand mixer), beat the butter for 1 minute until smooth, scraping down the sides as needed.

Cream cheese: Add cream cheese then beat for 1 minute until smooth.

Icing sugar: Add 1/3 of the icing sugar, then starting on the lowest speed (to avoid a powdery explosion!), beat until mostly incorporated. Add half the remaining icing sugar, beat it in, then the remaining icing sugar.

Fluff it! Beat on high for 2 minutes until fluffy. Add vanilla and salt, beat briefly to incorporate.

Pipe: Transfer to piping bag fitted with a round tip (or ziplock bag with snipper corner). Pipe on to cupcake, sprinkle with chopped walnuts or pecans if desired.