Place the flour in a mixing bowl and make a well in the middle. Add the yeast with 1/2 the milk and mix well. Cover and let rise for 15 minutes.
Add melted butter, remaining milk, egg and salt then knead well to make a smooth dough. Preheat oven to 50 C, or the lowest possible setting. Turn the oven off and place the dough inside, covered. Or, let rise, covered, in a warm location. Let rise for 15 minutes. Knead again and let rise for another 15 minutes.
Divide the dough into one large part for the body, 1 small part for the head and 5 very small parts for the head, ears, feet and tail. Shape each part to make a bunny. Brush the contact surfaces with a little water to help them stick. Place on a greased baking tray and let rise for 30 minutes in a warm place.
Preheat oven to 180 C / Gas 4.
Beat the egg yolk and brush over the bunny. Decorate with seeds if you like. Bake until golden brown, 20 to 25 minutes.