• Step 1: Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
• Step 2: In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
• Step 3: In a large bowl, cream the 1/2 cup of unsalted butter and granulated sugar until light and fluffy, about 2-3 minutes. Beat in the eggs one at a time, then stir in the 1 teaspoon of vanilla extract.
• Step 4: Add the drained crushed pineapple and buttermilk to the butter mixture, alternating between the two and mixing just until combined. Do not overmix.
• Step 5: Divide the batter evenly between the prepared cake pans. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Allow the cakes to cool in the pans for 10 minutes, then transfer them to a wire rack to cool completely.
• Step 6: In a large bowl, beat the 1 cup of unsalted butter until light and fluffy, about 2-3 minutes. Gradually add the confectioners’ sugar, pineapple juice, 1/2 teaspoon of vanilla extract, and a pinch of salt, mixing until the frosting is smooth and creamy.
• Step 7: Place one cooled cake layer on a serving plate or cake stand. Spread a generous amount of the pineapple frosting over the top. Top with the second cake layer and frost the top and sides of the cake with the remaining frosting, creating a smooth, even finish.
• Step 8: Refrigerate the cake for at least 30 minutes before serving to allow the frosting to set.