Mocha Delight Muffins

Ingredients

• 1 teaspoon vanilla extract
• 0.5 cups unsalted butter, melted
• 1 teaspoon baking soda
• 6 ounces mini dark chocolate chips
• 0.5 cups granulated sugar
• 1.5 cups all-purpose flour
• 0.5 cups low-fat buttermilk, stirred
• 2 tablespoons ready espresso
• 0.5 cups unsweetened cocoa powder
• 2 large eggs at room temperature