01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper and set aside.
02 - In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until evenly distributed.
03 - In a large bowl, combine the granulated sugar, melted coconut oil, unsweetened applesauce, pineapple juice, and vanilla extract. Stir until the mixture is smooth and well incorporated.
04 - Gradually add the dry ingredient mixture to the wet ingredients, stirring until a soft dough forms. Fold in the lemon zest if using.
05 - Scoop tablespoon-sized portions of dough and roll into balls. Arrange on the prepared baking sheets, spacing them 2 inches apart. Gently flatten each ball with your palm or the bottom of a glass.
06 - Bake for 10 to 12 minutes, until the edges are just beginning to turn golden. Do not overbake. Allow the cookies to cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.
07 - In a mixing bowl, beat the softened vegan butter with the pineapple puree and vanilla extract until creamy. Gradually add the sifted powdered sugar and a pinch of salt, beating until the filling is light and fluffy.
08 - Once the cookies are completely cool, spread or pipe a generous layer of pineapple vanilla cream onto the flat side of half the cookies. Top with the remaining cookies, flat side down, to form sandwiches.
09 - Refrigerate the assembled cookies for 20 minutes to allow the filling to set before serving.