Preheat the oven to 190C or 375F and line a baking sheet with parchment paper.

In a saucepan, combine the milk, water, butter, salt, sugar, and vanilla. Heat over medium heat until it boils. Remove from the heat and add the flour all at once. Mix with a rubber spatula until no dry ingredients are left.

Bring back to the heat and cook the dough for 2-3 minutes, mixing continuously with the rubber spatula until a whiteish film forms on the bottom of the pan and the dough forms a ball with a homogenous consistency. Remove from the heat.

Place the dough in a stand mixer fitted with a paddle attachment (you can also use a bowl and a wooden spoon). Beat the dough on low for a minute or until it’s not quite hot to the touch but still very warm (the ideal temperature should be 110F-140F or 43C-60C ).

When ready, start adding the eggs a little at a time and beat on medium until incorporated. Then, add more eggs. Repeat until all eggs are incorporated. Scrape the sides and the bottom of the bowl and beat one last time just for a few seconds to mix. The dough should be smooth and when you lift the paddle, it should slowly fall from it leaving a V-shaped tail. It should be firm enough to hold a shape when piped out but moist. If this texture is achieved before all eggs are incorporated, stop adding them. If the texture is not there yet after you’ve added all the eggs, you need to add ¼ - 1 extra egg.

Transfer the dough into a piping bag fitted with a round nozzle (such as Wilton 2A). Keep the piping nozzle facing straight down toward the piping surface (0.5” or 1 cm away from it) and pipe 30 even 1 ½" or 4cm rounds. Apply an even pressure, letting the rounds expand a little bit up and sideways. Leave 1" in between them. Work in batches if needed. The dough can wait in the piping bag while the first batch is in the oven. Dampen your finger with water and press down all the pointy tails on top of each round.

Bake for about 25 minutes or until they’ve puffed up and golden brown on the top and the sides.

Remove from the oven and let cool down on the baking sheet for 10 minutes, then place on a cooling rack to cool down completely. Pipe the second batch and bake.

In a bowl, combine the eggs, cornstarch, half of the sugar, and salt.

Heat the milk in a saucepan with the rest of the sugar just until it starts simmering. Remove from the heat and slowly pour into the bowl with the egg mixture, whisking vigorously. Then, pour the mixture back into the saucepan through a sieve and return to the heat.

Cook the mixture over medium heat, whisking continuously. When it thickens, lower the heat to medium-low and cook for 2 minutes while whisking. Remove from the heat. The mixture should resemble pudding and have no cornstarch flavor left. Add the butter and vanilla to the hot mixture and mix until incorporated.

Pour the cream into a large dish, cover it with plastic wrap so it touches the mixture, and place it in the fridge to cool down.

When the profiteroles are at room temperature, remove the cream from the fridge and whisk to make it smooth again. Place in a piping bag.

Cut a hole in the bottom of each profiterole with a small knife.

Cut off the tip of the pastry bag with cream, just enough to insert into the holes. Fill the profiteroles with the cream. There should be around 30g of filling per profiterole.

In a bowl, add the chocolate.

Heat the heavy cream in a saucepan until it starts simmering. Remove from the heat and pour over the chocolate. Let it sit for 2 minutes. Then, stir until homogenous in consistency.

Dip the top of each profiterole into the glaze and shake off the excess. Place on a plate to set for 10 minutes before serving.