FOR THE CUPCAKES: – 1 cup (120g) all-purpose flour – 1 cup (200g) granulated sugar – 1 cup (85g) unsweetened cocoa powder – 1 teaspoon baking soda – 1/2 cup (118ml) buttermilk – 1/4 cup (59ml) vegetable oil – 1/2 cup (118ml) warm water – 1 large egg – 1 teaspoon vanilla extract FOR THE FROSTING: – 1 cup (226g) unsalted butter, softened – 3 & 1/2 cups (385g) confectioners' sugar, sifted – 1/2 cup (42g) unsweetened cocoa powder – 1/4 cup (59ml) heavy cream – 1 & 1/2 teaspoons vanilla extract – 1/4 teaspoon salt – sprinkles, for garnish