Prepare the Cake:
Preheat your oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
In a large bowl, cream together butter and sugar until light and fluffy.
Add eggs one at a time, beating well after each addition.
In a separate bowl, whisk together flour, baking powder, and salt.

Gradually add the dry ingredients to the creamed mixture, alternating with pineapple juice, beginning and ending with the flour mixture. Stir in vanilla extract.
Pour the batter into the prepared cake pan.

Make the Pineapple Filling:
In a small saucepan, combine crushed pineapple, sugar, and cornstarch. Cook over medium heat until thickened, about 5-7 minutes. Let it cool slightly.
Once slightly cooled, spoon the pineapple filling over the cake batter in the pan, and gently swirl it with a knife.

Bake:
Bake for 50-60 minutes or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for 10 minutes, then turn out onto a wire rack to cool completely.

Prepare the Glaze:
In a small bowl, mix powdered sugar with pineapple juice (adjust the juice to get the desired consistency).
Drizzle the glaze over the cooled cake.
Sprinkle lemon zest over the glaze if using.

Serve