Preheat the Oven and Prepare the Pan:

Preheat your oven to 350°F (175°C). Grease and flour a 9×13-inch baking pan.
Prepare the Cake Batter:

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
Gradually add the dry ingredients to the creamed mixture alternately with the pineapple juice and sour cream, beginning and ending with the dry ingredients. Mix until just combined.
Bake the Cake:

Pour the batter into the prepared baking pan and spread it out evenly.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Remove from the oven and let the cake cool in the pan on a wire rack.
Prepare the Pineapple Glaze:

In a small saucepan, combine the pineapple juice and granulated sugar. Bring to a boil over medium-high heat, stirring occasionally.
In a small bowl, mix together the cornstarch and cold water until smooth.
Gradually whisk the cornstarch mixture into the boiling pineapple juice.
Cook, stirring constantly, until the glaze thickens, about 1-2 minutes.
Remove from heat and stir in the butter until melted and smooth.
Glaze the Cake:

While the cake is still warm, poke holes all over the top using a fork or toothpick.
Pour the warm pineapple glaze evenly over the top of the warm cake, allowing it to soak in.
Let the cake cool complet