plum kuchen

INGREDIENTS

• 2 1/4 teaspoons or 1 (1/4-ounce) package active dry yeast
• 1/4 cup warm water (105–110°F)
• 2 cups (267 grams) plus 2 tablespoons (18 grams) all-purpose flour, divided
• 1 cup sugar (220 grams), divided
• 1/2 teaspoon salt
• 1/2 cup plain whole-milk yogurt (124 grams) (preferably Greek-style, but I used regular yogurt and it worked just fine) at room temperature
• 1 large egg, warmed in shell in warm water five minutes
• 1 1/2 teaspoons grated lemon zest
• 1 teaspoon pure vanilla extract
• 1 1/4 sticks (5 ounces or 142 grams) unsalted butter, cut into tablespoons and softened, divided
• 3/4 pound firm-ripe plums (about 4 small), halved and pitted