Creating these exquisite Chocolate Drizzle Cream Puffs is a rewarding process. Follow these detailed instructions carefully for success:

Part 1: Making the Choux Pastry (Pâte à Choux)

1. Prepare the Base: In a medium saucepan, combine the water, butter, sugar, and salt. Place the saucepan over medium heat.
2. Melt and Boil: Heat the mixture, stirring occasionally, until the butter is completely melted and the mixture comes to a rolling boil. It’s crucial that it reaches a full boil, not just simmering, to ensure proper hydration of the flour.
3. Add Flour and Cook: Remove the saucepan from the heat. Immediately add all the sifted all-purpose flour to the boiling mixture. Using a wooden spoon or spatula, vigorously stir the flour into the liquid until a smooth dough forms and pulls away from the sides of the pan. This is called a “panade.” Continue to stir and cook the dough over low heat for about 1-2 minutes. This step is essential to dry out the dough slightly, which helps in creating light and airy puffs. The dough is ready when a thin film forms on the bottom of the pan.
4. Cool Slightly: Transfer the dough to a mixing bowl. Let it cool slightly for about 5-10 minutes. This is important so that the eggs don’t cook when added. You want the dough to be warm, not hot.
5. Incorporate Eggs Gradually: Crack one egg into a small bowl and lightly beat it. Add about one-third of the beaten egg to the slightly cooled dough. Mix thoroughly with a wooden spoon or electric mixer (on low speed) until the egg is fully incorporated and the dough becomes smooth again. Repeat this process, adding the remaining beaten egg in two more additions, mixing well after each addition. The dough should be smooth, glossy, and slowly fall from a spoon in a thick ribbon or form a “V” shape. The consistency is key here; you may not need all of the fourth egg, or you might need a little more if your eggs are smaller. The goal is a dough that is pipeable but not too runny.
6. Preheat Oven and Prepare Baking Sheet: Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper or a silicone baking mat.
7. Pipe or Spoon the Pastry: Transfer the choux pastry dough into a piping bag fitted with a large round tip (or a star tip for a more decorative look, though round is recommended for even puffing). Pipe mounds of dough onto the prepared baking sheet, about 1 ½ inches in diameter and about 2 inches apart to allow room for expansion. If you don’t have a piping bag, you can use two spoons to scoop and shape the dough into mounds.
8. Bake: Place the baking sheet in the preheated oven and bake for 20-25 minutes, or until the cream puffs are puffed up, golden brown, and sound hollow when tapped lightly on the bottom. Do not open the oven door during the first 15 minutes of baking, as this can cause the puffs to deflate.
9. Cool Completely: Once baked, turn off the oven and slightly open the oven door, leaving the cream puffs inside for another 10 minutes to dry out further. This helps prevent them from collapsing. Then, remove the baking sheet from the oven and let the cream puffs cool completely on a wire rack. Cooling completely is crucial before filling them with cream.

Part 2: Making the Cream Filling

1. Chill Bowl and Whisk: Place your mixing bowl and whisk attachment (or beaters if using a hand mixer) in the freezer for about 15-20 minutes. This ensures the heavy cream stays cold, which is essential for proper whipping.
2. Whip the Cream: Pour the cold heavy cream into the chilled bowl. Beat with an electric mixer on medium speed until soft peaks begin to form.
3. Add Sugar and Vanilla: Gradually add the sifted powdered sugar and vanilla extract to the whipped cream. Continue to beat on medium-high speed until stiff peaks form. Be careful not to overwhip, or you’ll end up with butter! You want stiff peaks that hold their shape but are still smooth and creamy.
4. Transfer to Piping Bag (Optional): If desired, transfer the whipped cream into a piping bag fitted with a star or round tip for easier and neater filling of the cream puffs.

Part 3: Assembling and Drizzling

1. Prepare Cream Puffs for Filling: Once the cream puffs are completely cool, use a serrated knife to carefully slice them in half horizontally. Alternatively, you can use a small paring knife to poke a hole in the bottom of each puff.
2. Fill with Cream: Fill each cream puff with the prepared whipped cream. If you sliced them in half, spoon or pipe the cream onto the bottom half and then replace the top half. If you made a hole in the bottom, pipe the cream into the hole until the puff feels nicely filled.
3. Make the Chocolate Drizzle: Place the semi-sweet chocolate chips and vegetable oil (or coconut oil) in a microwave-safe bowl. Microwave in 30-second intervals, stirring after each interval, until the chocolate is melted and smooth. Be careful not to overheat the chocolate. You can also melt the chocolate in a double boiler over simmering water.
4. Drizzle with Chocolate: Once the chocolate is melted and smooth, let it cool slightly for a minute or two (if it’s too hot, it will melt the cream). Drizzle the melted chocolate over the filled cream puffs in a decorative pattern. You can use a spoon, a fork, or a piping bag with a small tip for drizzling.
5. Set and Serve: Allow the chocolate drizzle to set for a few minutes before serving. This allows the chocolate to firm up slightly and become less messy.