Saffron-Vanilla Snickerdoodles

INGREDIENTS

• about 30 threads of saffron (to yield 1/8 teaspoon ground saffron)
• 1/2 vanilla bean
• 2 tablespoons milk
• 2 cups (9.9 oz / 280 g) all-purpose flour
• 1 teaspoon baking soda
• 1/2 cup (4 oz / 113 g) unsalted butter, at room temperature
• 1/2 cup (3.5 oz / 100 g) granulated sugar
• 1/2 cup (3.8 oz / 109 g) packed light brown sugar
• 1 teaspoon kosher salt
• 1 egg (1.8 oz / 50 g), at room temperature
• 1/2 teaspoon vanilla extract