Preheat your grill to high. Toast the bread on both sides until lightly golden.
Chop the drained kimchi and place in a mixing bowl with the grated cheddar. Crumble or break up the blue cheese with a fork and add to the bowl with the spring onions.
Beat in the egg and crème fraîche (or double cream) and mix everything together well.
Divide the mixture between the four toasts and place under the grill. Grill for 4-5 minutes, until oozy with a golden-brown crust, then serve, perhaps with a watercress salad if a main meal.