For the Cake Batter:

1. Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. Whisk together flour, baking powder, baking soda, and salt.
3. Cream butter, granulated sugar, and brown sugar until light and fluffy.
4. Beat in eggs one at a time, then add vanilla extract.
5. Mix in crushed pineapple with juice.
6. Gradually add dry ingredients to wet ingredients, alternating with milk. Mix until combined.

For Baking the Cake:

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

For the Pineapple Frosting:

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

For Assembling the Cake:

1. Level cake layers if necessary.
2. Layer with frosting.
3. Frost the entire cake.
4. Garnish with pineapple slices, toasted coconut flakes, and maraschino cherries.