Preheat oven to 350˚F and line muffin pan with parchment cups.
In a medium bowl, beat egg. Add oil, buttermilk, sugar and vanilla until blended.
Add flour, baking soda, cinnamon and salt. Mix until incorporated.
Stir in pineapple, grated carrots, nuts (optional) and coconut.
Pour into muffin pan and bake 25-30 min or until toothpick inserted comes out clean.
Allow to cool 5 minutes in muffin tin before transferring to a cooling rack. Cool completely before storing
In a medium mixing bowl, whip softened cream cheese with butter, then add lemon juice and vanilla.
Add powdered sugar, 1 cup at a time, until you reach the consistency needed to pipe or spread onto cupcakes. You may not need all the powdered sugar, or you may need a touch more.
Spread frosting onto cooled cupcakes, or use a piping bag and a 1M Wilton piping tip to top each cupcake with a decorative touch.