Starbuck's Chocolate Fudge Squares with Mocha Glaze recipe - from the Good and Simple Eats Family Co

Ingredients

• 1/2 cup unsalted butter, at room temperature (1 stick; see note)
• 1 cup granulated sugar
• 1 egg
• 1 cup all-purpose flour
• 1/4 teaspoon baking powder
• 2 ounces unsweetened chocolate, melted
• 1/2 cup milk
• 1 teaspoon vanilla extract
• 1/2 cup chopped walnuts
• Glaze
• 1 cup powdered sugar
• 1 tablespoon unsalted butter, at room temperature
• 1 ounce unsweetened chocolate, melted
• 1/4 cup brewed double-strength coffee, preferably
• from dark-roasted beans