Streusel Küchen Recipe | Epicurious

Ingredients

• 1 cup all purpose flour
• 2/3 cup (packed) golden brown sugar
• 1/3 cup chopped walnuts
• 1/4 teaspoon salt
• 6 tablespoons (3/4 stick) unsalted butter, melted
• 2 medium-size Golden Delicious apples, peeled, halved, cored, cut into 1/8-inch-thick slices
• 1/2 teaspoon ground cinnamon
• 1/8 teaspoon ground cloves
• 1 1/2 cups plus 2 tablespoons cake flour
• 1/3 cup cornstarch
• 1 1/2 teaspoons baking powder
• 1 cup plus 2 tablespoons unsalted butter (2 1/4 sticks), room temperature
• 2 cups powdered sugar
• 1 tablespoon finely grated lemon peel
• 1 vanilla bean, split lengthwise
• 3 large eggs plus 1 large egg yolk