Lemon Blackberry Muffins

INGREDIENTS

• 2 cups all-purpose flour
• 2 teaspoons baking powder
• 1/2 teaspoon salt
• 1/4 teaspoon baking soda
• 3/4 cup packed light brown sugar
• 2 eggs
• 3/4 cup buttermilk
• 1/4 cup unsalted butter, melted
• 1 teaspoon grated lemon zest
• 3 tablespoons fresh lemon juice, divided
• 1 teaspoon vanilla extract
• 1 cup fresh blackberries or 1 cup frozen blackberry, unthawed
• 2 tablespoons sugar