for that you could use the compare x event with the platform behavior on the toppings, example
for each (Topping)
topping compare x < player.x
topping simulate controll (left)
topping compare x > player.x
topping simulate controll (right)
Jumping would be a bit more complex the easiest way I can think of off the top of my head would be
keyboard on key pressed (space)
player create object (Jump_zone)
topping on collision with another object (Jump_zone)
topping simulate controll jump
if you do follow this approch make sure the jump zones get destroyed after around 10 seconds, make sure they have initially visable tuned off and make sure that default controlls are turned off for the toppings
enjoy :)