Using the mould, cut a heart out of the bread.
Spread butter on the bread.
Place it in a non-stick pan with the butter side facing down.
Crack the egg in a bowl, scoop the egg yolk & secure it in the middle of the hole in the pan. Slowly scoop the egg white around the yolk to fill up the rest of the space.
Slow heat till the bottom part of the egg is cooked. Lift up the toast to check, its ready when the bottom part of the egg doesn't stick onto the pan.
Pan fry the left over bread with the butter side facing down till golden brown.