In a medium bowl, using a hand mixer, beat the butter and sugar on medium speed until light and fluffy, about 2 minutes. Beat in the yogurt until well combined, then beat in the curry leaves, serrano, cilantro and kosher salt. Using a wooden spoon, fold in the flour and cheese until the dough just comes together. Turn the dough out onto a work surface and press into a ball. Roll the dough into a 1 1/2-inch-thick log, wrap tightly in plastic and refrigerate until firm, about 1 hour.