Heat a nonstick frying pan on stove add the butter toss in the sliced mushrooms add the shallots & garlic, cook for 8-10 mins stirring from time to time.
Pour in the wine and allow to boil off for 1 min before adding the stock.
Reduce the liquid by a third - this will only take a few minutes.
Add the cream and boil again, checking the seasoning. Mix in the spring onion greens and give a squeeze of lemon juice to sharpen the sauce - set aside off the heat but keeping warm.
Toast the rye bread on one side only - rub the toasted side with the cut face of the garlic clove.
Place rocket on a nonstick tray and lightly season. Place under the grill that toasted the bread (assuming that it will be off) the residual heat will soften the leaves. Failing that, put in a plastic bowl and season with salt and pepper and pop in microwave set on high for 30 seconds until wilted.
Place the rye toasted side up on plates, top with the wilted rocket then spoon over the creamy mushrooms and dust with a little cayenne pepper.