Chocolate Cupcakes with Chocolate Frosting

Ingredients

• 1/4 cup (2 ounces) unsalted butter, at room temperature
• 1 cup sugar
• 2 ounces semi-sweet chocolate chips, melted and cooled
• 2 large eggs, at room temperature
• 2 large egg yolks, at room temperature
• 1/2 cup plus 1 tablespoon vegetable or canola oil
• 1/3 cup full fat sour cream
• 2 teaspoons good quality vanilla extract
• 1 cup all-purpose flour
• 1/2 cup good quality cocoa powder
• 1 tablespoon espresso powder
• 1/2 teaspoon kosher salt
• 1/2 teaspoon baking soda
• 1/2 cup room temperature water