For Preparing the Cake Batter:

1. Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. In a bowl, whisk together flour, baking powder, baking soda, and salt.
3. In a separate large bowl, cream together the butter, granulated sugar, and brown sugar until light and fluffy.
4. Add eggs one at a time, beating well after each addition. Stir in vanilla extract.
5. Mix in the crushed pineapple with its juice.
6. Gradually add the dry ingredients to the wet ingredients, alternating with milk. Mix until just combined.

For Baking the Cake:

1. Pour the batter into the prepared cake pans.
2. Bake for 25-30 minutes or until a toothpick comes out clean when inserted into the center.
3. Let the cakes cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

For Making the Pineapple Frosting:

1. Beat the softened butter in a mixing bowl until creamy.
2. Gradually add the powdered sugar, mixing until smooth.
3. Fold in the drained crushed pineapple and coconut extract (if using).
4. Adjust the consistency with a splash of heavy cream if necessary.

For Assembling the Pineapple Heaven Cake:

1. If needed, level the cake layers.
2. Spread frosting between the layers and over the entire cake.
3. Garnish with fresh pineapple slices, toasted coconut flakes, and maraschino cherries.