In a small saucepan melt 2 tablespoons butter. Stir in flour to make a paste. Set roux aside.
Saute mushrooms, Cajun spice and garlic in 65g butter over medium-high heat for 2 minutes. Add oysters, corn, green beans and chilli. Saute for 1 1/2 minutes. Add stock and linguine and bring to a slight simmer.
Fold in roux until sauce thickens then reduce heat. Fold in parsley and scallions. Fold in crab meat and heat through. Serve immediately.