Heat the oil and butter in a wide saucepan and fry the onion and garlic gently for 7 minutes until soft and translucent.
Chop both types of mushrooms into decent sized chunks and add to the pan, turning the heat up to medium-high. After about 5 mins, when they begin to colour, add the Paprika and stir well, then add the flour and stir to coat the mushrooms.
Add the wine and stir well, deglazing the pan as you go to get all the flavours mixed in. Allow to boil for a minute or two, then add the stock and boil down for around 5 minutes until it begins to thicken.
Spoon in the double cream, mix well, allow to heat through. Add the lemon juice and season just before serving. Serve with rice, crusty bread, or tagliatelle pasta.