Sourdough Blueberry Muffins With Crumb Topping

Ingredients

• INGREDIENTS
• DRY INGREDIENTS
• 2 cups (240 g) all purpose flour
• 1 cup (200 g) granulated sugar
• 2 teaspoons baking powder
• ½ teaspoon baking soda
• ½ teaspoon salt
• 1 tablespoon corn starch
• zest of half a lemon
• 1 cup (150 g) blueberries (fresh or frozen)
• WET INGREDIENTS
• 8 tablespoons (113 g) butter (melted)
• 2 large eggs
• ½ cup (125 g) sourdough starter discard
• 3 tablespoons (45 g) sour cream (or plain Greek yogurt)
• 1 teaspoon (5 g) vanilla extract
• CRUMB TOPPING
• 3 tablespoons (45 g) butter ( melted)
• ½ cup (100 g) granulated sugar
• ½ cup (60 g) all purpose flour