Preheat oven to 325 degrees F. Line an 8-inch loaf pan with wax paper or nonstick foil and spray with cooking spray.
In a large bowl cream together sugar and butter until very light and fluffy (3-4 minutes). Mix in the eggs, greek yogurt (or sour cream), vanilla, lime zest, and lime juice until combined.
In a medium bowl whisk together flour and baking soda. Add dry ingredients to wet ingredients and stir by hand until combined (do not over-mix).
Pour batter into prepared pan. Bake 55-75 minutes until an inserted toothpick comes out clean (see note). Allow cake to cool completely on a wire rack.
When cake has cooled completely, prepare the glaze. Mix together powdered sugar, lime juice, coconut extract, and heavy cream (or half and half or milk) until smooth and pourable.
Pour glaze over the cooled cake, using a rubber spatula to spread the glaze evenly. Sprinkle with shredded coconut if desired. Allow to cool completely before slicing. Store leftovers in airtight container at room temperature up to three days or in the fridge up to 5 days.