Sift the flours into a large bowl, then make a well in the centre. Gradually whisk in the egg, egg white and milk until smooth. Leave to rest for 8 minutes.
Meanwhile, place the tomatoes in a heatproof bowl and pour over boiling water to cover. Leave for 1–2 minutes, then drain, cut a cross at the stem end of each tomato and peel off the skins. Deseed and chop the flesh.
Heat half the butter in a frying pan, add the tomatoes, mushrooms and herbs and cook for 5 minutes. Keep warm.
Melt the remaining butter in 2 frying pans until foaming, then pour in enough of the batter to just cover the bases. Cook each pancake for about 3 minutes, then turn over and cook for a further 2 minutes. Remove from the pans and keep warm. Repeat with the remaining batter to make 8 pancakes.
Divide the vegetable mixture between the pancakes and serve sprinkled with the cheese.