Preheat your oven to 350°F (175°C). Grease and flour (using GF flour) one 9-inch round cake pan or line with parchment paper.
In a medium bowl, whisk together the gluten-free flour blend, baking powder, baking soda, and salt. Set aside.
In a large bowl, cream the softened butter and sugar together until light and fluffy.
Beat in the eggs one at a time, mixing well after each addition. Stir in the vanilla extract and lemon zest.
In a separate small bowl, whisk together the coconut milk and lemon juice.
Gradually add the dry ingredients to the wet ingredients, alternating with the coconut milk mixture, beginning and ending with the dry ingredients. Mix until just combined. Do not overmix.
Fold in the shredded coconut gently.
Pour the batter into the prepared pan and spread evenly.
Bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes before inverting it onto a wire rack to cool completely.
While the cake cools, prepare the glaze: Whisk together the powdered sugar and 1 tablespoon of lemon juice until smooth. Add a few more drops of juice if needed to reach a drizzling consistency.
Drizzle the glaze over the cooled cake. Serve plain or top with extra toasted coconut if desired.
Notes
If your gluten-free flour blend does not contain xanthan gum, add 1/2 teaspoon to the dry ingredients.
For a stronger coconut flavor, use unsweetened coconut milk and toast the shredded coconut before adding it to the batter.
You can make this cake dairy-free by substituting the butter with a solid dairy-free baking stick.