Hortensia's Best-Ever Chocolate Pound Cake

INGREDIENTS

• Cocoa powder or confectioners' sugar, to finish
• 2 teaspoons vanilla extract
• 1 1/2 cups unsalted butter, at room temperature
• 5 eggs
• 2 3/4 cups sugar
• 2 teaspoons espresso extract (or substitute 2 teaspoons instant coffee dissolved in 1 tablespoon buttermilk)
• 1/4 cup sugar, to line pan
• Unsalted butter, at room temperature (but still firm), to brush pan
• 1/2 teaspoon baking soda
• 1 1/4 cups buttermilk
• 1 teaspoon baking powder
• 1 teaspoon salt
• 1 cup plus 2 tablespoons unsweetened Van Leer Dutch process medium cocoa
• 2 cups all-purpose flour