Sourdough Cinnamon Crumb Cake

Name: Sourdough Cinnamon Crumb Cake
Prep time: 30 min
Cook time: 50 min
Total time: 1 h 20 min
Cuisine: American
Ingredients: 2 cups (240g) King Arthur Unbleached All-Purpose Flour; 1 cup (198g) granulated sugar; 1 1/2 teaspoons cinnamon; 1/2 teaspoon table salt; 1 teaspoon King Arthur Pure Vanilla Extract; 1/2 teaspoon almond extract; 12 tablespoons (170g) unsalted butter, melted; 8 tablespoons (113g) unsalted butter, at room temperature, at least 65°F; 2 large eggs, at room temperature; 1 tablespoon King Arthur Pure Vanilla Extract; 1 cup (227g) sourdough starter, unfed/discard; 1 tablespoon potato flour or 2 tablespoons dried potato flakes (instant mashed potatoes); 1 teaspoon baking powder; 1/2 teaspoon baking soda; 1/4 cup (57g) milk, at room temperature; confectioners' sugar, optional