Cookbook challenge, week 37: Steak, Guinness and cheese pie with puff pastry lid

The theme for week 37 is hearty, and I found a recipe in Jamie Oliver's Jamie at Home that sounded delicious and that I thought J would enjoy: a steak, Guinness and cheese pie.

Ingredients:
olive oil
3 medium red onions, peeled and chopped (I used 3 small white onions)
3 cloves of garlic, peeled and chopped
30g butter, plus extra for greasing
2 carrots, chopped
2 sticks of celery, trimmed and chopped
4 field mushrooms, sliced (I used 7 white mushrooms)
1kg beef, cut into 2cm cubes
a few sprigs of fresh rosemary, leaves picked and chopped
sea salt and freshly ground black pepper
440ml can of Guinness
2 heaped tbs plain flour
200g grated cheese (I used less)
puff pastry
1 egg

In a large ovenproof pan (I used an electric frypan) heat a glug of olive oil on a low heat.
Add the onions and fry gently for about 10 minutes.
Increase the heat and add the garlic, butter, carrots, celery and mushrooms, and mix everything together well.
Stir in the beef, rosemary, a pinch of salt and a level teaspoon of pepper.
Fry for 3-4 minutes then add Guinness, stir in the flour and add just enough water to cover. Bring to a simmer, cover and place in an oven at 190ºC for 2.5 hours (I used a slow cooker on high for 4 hours), stirring occasionally.
If it is too liquidy after cooking, reduce the liquid over heat or add some more flour.
Remove from the heat and stir in half of the cheese, then season.
Leave to cool slightly (you can do up until this step a day ahead).
Grease an appropriately sized pie dish, then line with a sheet of puff pastry, leaving the edges dangling over the side.
Tip pie mixture into the dish, then scatter with the rest of the cheese.
Brush the edge of the pastry with egg.
Cut out a lid-sized shape of puff pastry and place it over the top of the pie, folding the overhanging bottom pastry over it.
Brush the top with egg then bake in a preheated 190ºC oven for 45 minutes, until puffed and golden.

I used a smaller pie dish, around 7 inches in diameter, and this only used half the pie mixture. I've saved the rest to use another time - I think I will make individual mini pies with it (as it was still a little sloppy when serving as you can see below). The pie was great, with a beautiful and rich (and hearty!) filling. Served with some steamed broccoli and beans, it made a great meal.