Copycat Costco Double Chocolate Muffins

Ingredients

• 1 3/4 cups all-purpose flour (spooned and leveled )
• 2/3 cup unsweetened cocoa powder (sifted if clumpy)
• 1 Tbsp. baking powder
• 1 tsp. baking soda
• 1 tsp. salt
• 1 tsp. espresso powder (optional)
• ½ cup butter, unsalted (melted and slightly cooled )
• 1 ¼ cup granulated sugar
• 2 large eggs (room temperature)
• 2 tsp. vanilla extract
• 3/4 cup buttermilk* (room temperature )
• 1/2 cup sour cream (room temperature)
• 2 cups semi-sweet chocolate chips (divided)