No Bake Pistachio White Chocolate Cookies

3/4 cup creamy no-stir sunflower seed or almond butter
1 cup white chocolate chips (about 6 ounces), divided
1 cup quick-cooking oats
3/4 cup dried cranberries, coarsely chopped
1/4 teaspoon kosher salt
1/2 cup plus 1 tablespoon chopped, unsalted pistachios (about 2.3 ounces), divided
1/2 teaspoon vegetable oil

Heat sunflower seed butter and 3/4 cup chips in a medium heatproof bowl set over a medium pot of barely simmering water (bottom of bowl should not touch water), stirring occasionally, or in short bursts in the microwave, stirring in between bursts, until melted and smooth. Add oats, cranberries, salt, and 1/2 cup pistachios; stir gently to combine.
Spoon mixture by the tablespoonful onto a parchment-lined sheet tray. Gently press balls in the center to flatten. Chill until set, about 10 minutes.
Meanwhile, heat oil and remaining 1/4 chips in a medium heatproof bowl set over a medium pot of barely simmering water (bottom of bowl should not touch water), stirring occasionally, or in short bursts in the microwave, stirring in between bursts, until melted and smooth.
Drizzle cooled cookies with melted chocolate, top with remaining 1 Tbsp. pistachios, and chill until set, about 5 minutes.