PAVLOVA
Preheat oven to 250°F. Draw a 9-inch circle on a piece of parchment paper. Flip the paper so ink does not get on the meringue and set aside.
Whip whites, salt, and vanilla seeds on high in a mixer until firm. With the motor running, add sugar, a spoonful at a time, until whites are glossy and very stiff.
Add potato starch, cocoa powder, and espresso powder and gently fold into meringue with a spatula.
Transfer meringue to prepared parchment paper. Form meringue into a rustic bowl. It's not necessary to make it perfect. Just be sure to make the center thick enough to support the filling.
Bake pavlova at 250°F for 1 ½ hours. Turn off the oven and do not open the door for at least 6 hours or, better yet, overnight. The residual heat will crisp up the meringue and keep humidity out.
Place pavlova on a serving platter. Spoon chocolate pudding onto pavlova. Garnish with chocolate shavings, chocolate-covered coffee beans, and whipped cream.
BITTERSWEET CHOCOLATE PUDDING
In a medium bowl, whisk sugar, potato starch, salt, and egg yolks together. Set aside.
In a small pot, heat milk on medium-low until you see just a whiff of steam. Do not scald milk. Whisk milk into egg yolk mixture, a bit of time, until all milk is incorporated.
Return milk mixture to pot and cook, stirring constantly, until a thick pudding is formed. Cook and let mix bubble for 1 minute to cook out raw starch flavor.
Strain pudding through a sieve into a mixing bowl and stir in chocolate, butter, and vanilla beans.
Cover surface with parchment paper and chill for at least 4 hours, or overnight. Once chilled, use to fill baked pavlova.