Heart-Shaped Chocolate Éclairs
1 large egg 1 teaspoon cocoa powder, or to taste 1 teaspoon powdered sugar, or to taste 1 vanilla bean 2 cups whole milk 2 large egg yolks 2 large eggs 4 tablespoons cold unsalted butter, cubed 4 tablespoons unsalted butter, cubed 5 tablespoons cornstarch ½ cup all-purpose flour ½ cup fresh raspberries, or to taste ½ cup heavy cream ½ cup water ½ cup white sugar ½ teaspoon kosher salt ¾ cup dark chocolate chips