Double Chocolate and Mint Cookies

INGREDIENTS

• 2 tablespoons unsalted butter, at room temperature
• 1 cup flour
• 2/3 cup sugar
• 1/4 teaspoon salt
• One 4.67-ounce package chocolate mint thins, such as Andes, chopped into 1/2-inch pieces
• 1 teaspoon vanilla extract
• 2 tablespoons unsweetened cocoa powder
• 6 ounces semisweet or bittersweet (60-percent) chocolate, chopped into 1/2-inch pieces
• 1 teaspoon baking powder
• 2 large eggs, at room temperature