In a large pot, combine the whole chicken with chopped onion, bay leaves, thyme, diced carrot, and cloves. Add enough water to cover the chicken completely, then bring to a boil. Reduce heat and let simmer for about one hour until the chicken is tender.

Carefully remove the chicken from the pot and let it cool slightly. Shred the chicken using two forks, discarding the bones and skin. Strain the remaining stock to remove solids and cool in the refrigerator.

In a large pot, melt a knob of butter over medium heat. Add diced onions, sliced leeks, and grated carrots. Sauté for 5-7 minutes until soft and fragrant. Pour in white wine and let reduce, then stir in flour to create a roux. Whisk in chilled stock and cream to form a creamy filling.

Stir in shredded chicken, Dijon mustard, grated Parmesan cheese, and a sprinkle of salt and pepper to the filling. Mix well and let cool to room temperature.

Preheat your oven to 180°C (356°F). Roll out half of the butter puff pastry and line your pie dish, leaving enough overhang. Spoon the cooled filling into the pastry base evenly and cover with remaining pastry, sealing edges well. Make slits in the top crust for steam to escape.

Chill assembled pie in the refrigerator for at least 30 minutes. Then bake in preheated oven for 55-60 minutes until top is golden brown and flaky.

Let the pie cool for 5 minutes before serving. This helps the filling set slightly and makes it easier to cut.