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["Heat an oven to 350 F. Line the wells of muffin pan with papers and set aside.", "Sift the flour, baking powder, cardamom, and salt into a bowl and set aside.", "Add the butter and sugar to the bowl of a standing mixer fitted with the paddle attachment. Cream the butter and sugar on medium speed until light and fluffy, about 3minutes. Scrape down the sides of the bowl, add the egg, and mix well until combined.", "Add half of the flour mixture, the milk and vanilla, and the remaining flour mixture, mixing just until combined and scraping down the sides of the bowl between each addition.", "Evenly distribute the batter among the lined cups and bake until a toothpick comes out with a few crumbs attached and the edges are pale golden, about 17 minutes for regular sized cupcakes and 12 for minis.", "Let the cupcakes cool in the pan for a few minutes, then transfer to a rack to cool completely.", "Bring 1-2"" of water to a simmer in a saucepan that is wide enough for the bowl of your mixer to sit on top of it (but not so big that the bowl falls in).", "Add the egg whites and sugar to the mixer bowl. Whisk well to combine, then place over the pot of simmering water. Whisk constantly until the sugar has dissolved and the mixture is opaque and thick, about 3 minutes.", "Transfer the bowl to the mixer and attach the whisk attachment. Start on low speed and over the course of 30 seconds, bring the speed up to high. Whip on high speed until the whites are thick and glossy and the bowl is cool to the touch, about 7 minutes.", "While the whites are whipping, cut the butter into tablespoon-sized chunks. It's important that the butter is not too warm, so if it's squishy, put it in the fridge for a while so that it's somewhat firm but still pliant.", "When the whites are cool, scrape down the sides of the bowl and lower the speed to 8. Add 2 tablespoons of the butter and whip until combined, about 10 seconds. Continue with the remaining butter, waiting 10 seconds between each addition.", "When all the butter has been added, turn the speed to high and whip until the mixture comes together to form a thick frosting. This may take a while depending on how hot or humid it is, but don't lose faith - it will come together! After the frosting comes together, continue to mix on medium-high speed for another minute.", "Scrape down the sides of the bowl, then add half of the mango puree. Mix on low speed, then increase the speed to high to combine fully. Scrape down the sides of the bowl and repeat with the remaining mango puree.", "Scrape down the sides of the bowl and transfer the frosting to a piping bag fitted with a large star tip. Pipe the frosting onto the cupcakes once they are completely cooled."]
