Heat the butter in a pan. Add the peach and lemon juice and simmer, covered, for approx. 5 mins.
Spread 4 slices of bread with peanut butter and 4 with peach compote, to create 4 sandwiches, press down lightly. Combine the milk, egg and cinnamon in a deep dish, dip the sandwiches in the mixture, drain.
With the lid down, grill the sandwiches over/on a medium heat (approx. 200 °C for approx. 5 mins. on each side. Remove, halve the sandwiches. Mix the sugar and cinnamon, serve with the grilled sandwiches with the rest of the compote.