Slice the bread into 5 cm thick slices. Mix a splash of oil with the minced garlic and brush over the sliced bread. Bake in an oven set to 200C for 10 minutes.
Heat a fry pan with a splash of oil and toss in the mushrooms and fry for 5 minutes, then add the spring onions, fry until they just start to colour. Take off the heat and stir through the cream, mustard and parsley.
Using a large spoon press the centre of the baked cape seed to form a small hole.
Fill the hole with the creamy mushroom mix and top with the gruyere.
Turn the oven up to 250C and bake until the cheese has melted.