Blackberry Muffins

INGREDIENTS

• 1⁄3 cup sugar
• 3 Tbs. all-purpose flour
• Grated zest of 1⁄2 lemon
• 2 Tbs. unsalted butter, melted
• 1⁄3 cup pecans, finely chopped
• 2 cups all-purpose flour
• 3/4 cup sugar
• 2 tsp. baking powder
• 1⁄2 tsp. baking soda
• 1⁄2 tsp. ground cinnamon
• 1⁄4 tsp. salt
• 1 egg, beaten
• 5 Tbs. unsalted butter, melted
• 1 cup buttermilk
• 2 cups fresh blackberries or 2 1⁄2 cups frozen
• unsweetened blackberries, unthawed
• Unsalted butter for serving