Blend the dried porcini mushroom in blender until a powder is formed.
Toast the walnuts in the oven for 5 minutes and allow them to cook completely. Roughly chop them.
Mix everything for the stuffing together in a bowl. Season with salt and pepper.
Put two sheets of tin foil on your cutting board horizontally. Add a bit of olive oil.
Line the bacon strips vertically, slightly overlapping each other as shown. Put the chicken leg skin side down on the bacon. Season with salt and pepper. Add the filling and try to fill out any gaps in the meat. Roll the chicken closed and tighten well. Be careful not to tighten too much or the foil will rip.
Bring a shallow pan with water to just under a boil. Poach in a shallow pan for 25 minutes. The water should stay hot, just under a boil but not boiling.
Remove from the water, place on a plate with a paper towel and chill in the fridge. Set a timer for 30 minutes. Don't overchill.
Remove the tin foil carefully and dry on paper towels.
Get a cast iron pan medium-hot and add the oil. Once the oil is hot, sear the stuffed chicken until all sides are beautiful and golden brown. Be careful as the oil will splatter a bit if the chicken is not dry enough. Once the chicken is nicely browned on all sides, remove from the pan and keep in a warm place. Cover with a bit of tin foil.
Discard the cooking oil from the cast iron and put back on the heat. Add the dates and fry for 1-2 minutes. Deglaze with the wine. Reduce by half (about 1-2 minutes).
Add the chicken stock and reduce again by half (about 5 minutes). The sauce should fill about 250ml with the dates before you blend.
Transfer to a blender. Add the rest of the ingredients for the date sauce and blend. If the sauce is too thick then add more chicken stock. If it's too thin then add a bit more xanthan gum.
Slice the chicken with a bread knife or really sharp knife. Season with black pepper, Maldon salt and pour the sauce at the table. Enjoy with your favourite vegetable sides!