Chai Saffron-Plum Cake

recipe adapted from Cook’s Illustrated
yield: one 6-inch cake

INGREDIENTS

2 large eggs, room temperature
1/4 cup whole milk, room temperature
1 teaspoons pure vanilla extract
1/4 teaspoon saffron threads
3/4 cup, plus 2 tablespoons (3-1/2 ounces) cake flour
3/4 cup (5-1/4 ounces) granulated sugar
1 teaspoon baking powder
1/2 teaspoon fine sea salt
8 tablespoons (4 ounces/1 stick) unsalted butter, cut into 4 pieces, sof