Preheat your oven to 350 degrees. Spray a 13 by 9-inch baking dish with non-stick cooking spray and set it aside. This will ensure the cake slides out easily once it's baked.
In a medium mixing bowl, whisk together all-purpose flour, baking powder, baking soda, and salt for about 20 seconds. Setting this mixture aside will help in developing a good rise for your cake.
Take a fine mesh sieve and place it over a bowl. Pour the crushed pineapple into the sieve to drain all of the juice well. Reserve the canned juice for another use; you should have a little over 3/4 cup drained.
If you prefer a finer texture for the pineapple, you can pulse it in a food processor about 15 times or so to chop it up a bit. This is optional, but it can enhance the texture of the cake.
In another medium bowl, stir together the crushed pineapple with the pineapple juice concentrate and set it aside. This mixture will add the fruity flavor that we love.
In the bowl of an electric stand mixer fitted with the paddle attachment, whip together butter, granulated sugar, and lemon zest until the mixture is very pale and fluffy. This will take a few minutes but is crucial for the cake’s light texture.
Add the eggs one at a time, mixing well after each addition, then blend in the vanilla extract. This step helps to incorporate air, making the cake fluffy.
Next, add in 1/3 of the flour mixture and mix just until combined. Then, mix in 1/2 of the pineapple mixture and again mix just until combined. Repeat this process with the remaining flour and pineapple mixtures. This step is key in developing the cake's flavor and texture.
Carefully pour the batter into the prepared baking dish, spreading it into an even layer. This ensures that it bakes evenly.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, which should take about 30 to 35 minutes. Your kitchen will smell heavenly during this time!
Let the cake cool completely on a wire rack. Patience is key here; this step ensures your frosting doesn't melt!
For the frosting, in a clean bowl of an electric stand mixer, whip the remaining butter until fluffy. Add in heavy cream, vanilla, and powdered sugar, whipping on high speed for approximately 5 minutes until it's very light and fluffy. This frosting will add a rich and sweet layer to the cake.
Spread the frosting over the cooled cake and generously top it with shredded coconut. Then, cut it into slices and serve. Enjoy your Pineapple Cake!