1 to 1 1/2tablespoonsheavy creamhalf-and-half or milk
Preheat oven to 350 degrees F. Line a 9 × 4- inch loaf pan with parchment paper or aluminum foil. Coat with nonstick cooking spray.
In a large bowl, beat butter and sugar until light and fluffy. Add yogurt, eggs, vanilla, lime zest, and lime juice; blend until smooth. Add flour and baking soda; mix on low speed until smooth. Pour batter into prepared pan. Bake 60-80 minutes, until an inserted toothpick comes out clean. Allow cake to cool completely on a wire rack.
After cake has cooled completely, prepare the glaze. Using a hand mixer, mix powdered sugar, lime juice, coconut extract, and heavy cream in a medium bowl 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 in an airtight container, up to 5 days.