Ultimate Chicken and Mushroom Pie

Meanwhile, peel and grate the garlic (or use a garlic press).
Peel and chop the potatoes into 2cm chunks.
When your pan of water is boiling, add the potatoes and cook until you can easily slip a knife through, 15-20 mins.

Once the chicken has browned, add the garlic and stir-fry until fragrant, 30 secs.
Stir in the water for the sauce (see ingredients for amount), chicken stock paste, mustard and half the creme fraiche.
Bring to the boil, then lower the heat and simmer gently until the chicken is cooked through and the sauce has thickened, 5-6 mins. Season with salt and pepper. IMPORTANT: The chicken is cooked when no longer pink in the middle.

Transfer the chicken and mushroom filling to an appropriately sized pie dish.
Cover with the puff pastry (see ingredients for amount), trimming off any excess. Press some of the pastry over the side of the dish if you can, or just sit it on top. Make a small hole in the middle - this allows the steam to escape. TIP: Brush the pastry with a little milk if you have some.
Bake the pie on the top shelf of your oven until golden brown, 15-20 mins.

Once the potatoes are cooked, drain in a colander and return to the pan, off the heat.
Add the remaining creme fraiche and mash until smooth and velvety. Season with salt and pepper, then cover with a lid to keep warm.
Meanwhile, clean the (now empty) frying pan - you'll use it for the peas.