Blueberry-Filled Muffins

Ingredients (15)

• 2-3/4 cups all-purpose flour
• 1 cup sugar
• 1 tablespoon baking powder
• 3/4 teaspoon baking soda
• 3/4 teaspoon salt
• 2 large eggs, room temperature
• 1 cup buttermilk
• 1/2 cup butter, melted
• 2 teaspoons grated lemon zest
• 1/3 cup blueberry preserves
• TOPPING:
• 1/4 cup packed brown sugar
• 3 tablespoons all-purpose flour
• 2 tablespoons cold butter
• 1/4 cup chopped walnuts