Preheat the oven to 350ºF. Line a 12 cup muffin pan with paper liners.

In a medium mixing bowl, combine the flour, baking powder, and salt. Stir with a whisk to combine. Set aside.

In a separate mixing bowl, beat the butter on medium speed until creamy. Add the sugar, continue to beat for 3 minutes. 

With the mixer set to low, beat in the vanilla. Beat in the eggs, one at a time, mixing well after each addition. 

Beat in the crushed pineapple and its juice. Add the flour, mixing just until combined. 

Divide the batter evenly among the prepared muffin cups. Bake for 15 to 20 minutes or until a wooden toothpick inserted into the centers comes out clean. 

Cool the cupcakes in the pan for 5 minutes before transferring them to a wire rack to cool completely. Top with pineapple buttercream frosting.

Using a food processor, grind the freeze-dried pineapple into a fine powder. Sift the powder through a fine-mesh sieve and discard any large bits. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment or a large mixing bowl with a handheld electric mixer, beat the butter on medium-high speed until creamy and pale in color, about 5 minutes.

Add half the confectioners' sugar and beat on low speed just until the sugar has fully moistened, then turn the speed up to medium-high and beat until well incorporated, about 3-5 minutes.

Add the remaining confectioners' sugar and pineapple powder and beat on low speed just until the sugar has fully moistened, then turn the speed up to medium-high and beat until well incorporated, about 3-5 minutes.

Add the vanilla and salt. Turn the mixer on low speed and slowly add 1-2 tablespoons of the heavy cream. Turn the mixer up to medium-high and beat until the cream is well incorporated, about 3-5 minutes. (After 2 minutes stop and scrape down the sides and bottom of the bowl then continue mixing.)

Check the consistency of the frosting and add more cream, ½ tablespoon at a time, if needed. The frosting should be soft and spreadable but not so loose that it doesn't hold its shape.