1. Making the Choux Pastry (Éclair Shells)

The base of the éclairs is made from choux pastry, a delicate, light dough that puffs up beautifully when baked. Follow these steps to make perfect choux pastry:

1. Preheat the Oven: Set your oven to 375°F / 190°C and line a baking tray with parchment paper.

2. Heat the Liquids: In a saucepan, combine water, milk, butter, sugar, and salt. Heat over medium heat until the butter melts and the mixture begins to boil.

3. Add the Flour: Quickly add the flour to the boiling liquid, stirring vigorously with a wooden spoon or spatula until the dough pulls away from the sides of the pan and forms a smooth ball. This should take about 1-2 minutes.

4. Cool the Dough: Transfer the dough to a bowl and allow it to cool for about 5 minutes.

5. Add Eggs: Add the eggs, one at a time, beating well after each addition until the dough becomes smooth and pipeable.

6. Pipe the Shells: Using a piping bag with a 1–1.5 cm round tip, pipe 4–5 inch (10–12 cm) lines onto the prepared baking tray.

7. Bake: Mist the dough lightly with water and bake for 25-30 minutes, until the éclairs are puffed and golden brown.

8. Cool the Pastry: Once baked, turn off the oven, crack the door slightly, and let the éclairs dry out for 10 minutes before cooling completely on a wire rack.

2. Making Hazelnut Praline Paste

This rich, caramelized paste is the heart of the hazelnut flavor in your éclairs. Here’s how to make it:

1. Make Dry Caramel: Heat the sugar in a pan over medium heat until it melts and turns amber-colored.

2. Add Hazelnuts: Stir in the toasted hazelnuts, then pour the mixture onto parchment paper to harden.

3. Blend the Praline: Once cooled, break the caramelized hazelnuts into smaller pieces and blend them in a food processor until you achieve a smooth paste. This can take 5-8 minutes.

4. Store: Keep the praline paste in an airtight container until needed, or use store-bought praline paste if you prefer.

3. Making Hazelnut Praline Pastry Cream

This silky smooth filling combines the richness of hazelnut praline with traditional pastry cream. Follow these steps:

1. Whisk the Yolk Mixture: In a bowl, whisk together the egg yolks, sugar, and cornstarch until pale and smooth.

2. Heat the Milk: Heat the milk in a saucepan over medium heat until it’s just below boiling.

3. Combine the Mixtures: Slowly pour the hot milk into the egg mixture, whisking constantly to prevent the eggs from curdling.

4. Thicken the Cream: Return the mixture to the pot and cook, stirring constantly, until it thickens into a creamy custard.

5. Finish the Cream: Remove from heat and stir in the butter and hazelnut praline paste. Let the cream cool completely.

6. Optional Mousseline Texture: For a lighter, mousse-like filling, fold in whipped heavy cream before using.

4. Making Hazelnut Glaze

The glaze adds a glossy, nutty finish to the éclairs. Here’s how to make it:

1. Melt the Chocolate: Gently melt the white chocolate over a double boiler or in the microwave, stirring occasionally.

2. Add Praline Paste: Stir in the hazelnut praline paste until smooth.

3. Adjust Consistency: Add 1–2 tablespoons of heavy cream to adjust the texture of the glaze. It should be thick enough to coat the éclairs without dripping too much.

5. Assembling the Hazelnut Praline Éclairs

Now that you have all the components ready, it’s time to assemble the éclairs:

1. Prepare the Shells: Once the choux pastry shells have cooled completely, poke 2-3 small holes at the bottom of each shell or slice them lengthwise.

2. Fill the Eclairs: Using a narrow piping tip, fill each éclair with the hazelnut praline pastry cream until full.

3. Apply the Glaze: Dip the top of each éclair in the hazelnut glaze or spread the glaze with a spatula.

4. Garnish: Optionally, garnish with crushed caramelized hazelnuts, gold leaf, or cocoa nibs for extra elegance.

5. Chill: Refrigerate the filled éclairs for at least 30 minutes before serving to allow the flavors to meld.