Mix the almonds, walnuts, sesame seeds and sugar.
Unfold the pastry sheets. Place 2 sheets of pastry in the tin, brush with a little butter, repeat 3 times. Spread the filling on top, place another 2 sheets of pastry on top, brush with butter, repeat until there are no pastry sheets remaining. Make diamond-shaped incisions.
Approx. 25 mins. in the lower half of an oven preheated to 180°C. Remove from the oven, place on a tray.
Bring the water and sugar to the boil, reduce to a syrupy consistency for approx. 5 mins. Add the lemon juice, honey and rose water, cook for a further 5 mins. Pour the sugar syrup over the warm baklava, leave to cool.