Pre-heat the oven to 400°F.
Place the chicken in a skillet; add the onion, bay leaf, carrot, celery and parsley. Season with salt; add water to cover the chicken and bring to a boil. Reduce the heat to low and simmer gently for 15-20 minutes, depending on the size of the chicken breasts.
Meanwhile, place the dough on a floured surface. Sprinkle with poppy seeds, lemon zest and salt. Flour a rolling pin and gently roll the toppings into the dough. Using a pizza cutter or sharp knife, cut the dough into eight wedges; arrange on a nonstick or parchment-lined baking sheet and brush with the egg wash. Bake to golden, 15-20 minutes.
Place the chicken on a plate to cool and strain the poaching liquid. Return the skillet to stove and heat the EVOO, one turn of the pan, over medium heat. Add the leeks and garlic and season with salt and pepper. Cook to soften, 5-6 minutes, then add the flour and stir for 1 minute. Add the wine and reduce to evaporate; add the stock, cream and nutmeg, and bring to bubble. Add the Dijon and let thicken. Chop or shred the chicken; add the peas, tarragon, chicken and lemon juice to the sauce and stir to warm through. Remove from the heat and arrange the pie wedges on top.
Serve from the skillet into shallow bowls, removing the filling and one wedge of crust per portion.