Magical Chocolate Pie (Chess Pie)

Bahan-bahan (9 porsi)

• 1 unbaked Buttery Flaky Pie Crust (what I used) or All Butter Pie Crust*
• 1 large egg white, lightly beaten
• 1/4 cup (4 Tbsp; 56g) unsalted butter
• 2 ounces (56g) semi-sweet chocolate, finely chopped
• 1 cup (200g) granulated sugar
• 3 Tablespoons (16g) unsweetened natural or dutch-process cocoa powder
• 1 teaspoon espresso powder
• 1/4 teaspoon salt
• 1/4 cup (60ml) heavy cream
• 1 teaspoon pure vanilla extract
• 2 large eggs + 1 large egg yolk
• optional for serving: whipped cream