- Pour boiling water over dried mushrooms and set aside for 30 minutes.
- Place the garlic, dried chilli and olive oil in a cold pan and place over a low heat. When the garlic is sticky but not yet brown at all, add the thyme leaves. When their spluttering subsides, add the sliced onions, one knob of butter, a fair amount of salt and turn the heat right down.
- Stew onions in their natural juices with a lid partially covering, adding mushroom stock whenever it looks dry. Cook for roughly 1hr, until very broken down, adding the rehydrated, chopped mushrooms after 30mins. Remove from heat to cool (and store for future use if desired).
- Place a large pot of water on to boil and season generously with salt.
- Heat 1 tbsp oil in a high sided saute pan large enough to hold your pasta and sauce. Add the mushrooms and allow to fry briefly to get some colour on them (don’t move them around at this stage or they will boil). Add a knob of butter and toss. Once the butter has finished foaming season lightly with salt. Deglaze mushrooms with the wine and reduce by half.
- Meanwhile, drop your tagliatelle into the water.
- After 1 minute or so, add your slow-cooked onions, chopped parsley and a little of the pasta water. Once your pasta is very al dente, about 2 minutes, add to the pan along with a splash of pasta water. Finish with the parmesan, butter and a good toss around. Finish with a little pepper flake, if you fancy.