To make the rosti, preheat oven to 180°C.
Peel and chop potatoes and onions into pieces and place into TM bowl. Do not overfill bowl, make sure total amount in one batch is less than half the bowl. Chop 1 sec/speed 6 per batch. Turn out onto a large clean tea towel. Squeeze as much liquid out of the mixture as you can, over a sink.
Return dry potato onion mix to TM bowl and add all other ingredients apart from oil. Blend 6 sec/speed 6.
Meanwhile, heat enough oil to cover a small cast iron fry pan to 1 cm depth on a medium high heat. Dollop mixture into the hot oil and press flat to spread into a small pancake size.
Fry gently until golden, turning and repeating on the other side. Transfer to an oven tray and keep hot until you are ready to serve.
To make the Simple Hollandaise, Place all ingredients except melted butter into TM bowl and blend at least 60 sec/speed 10 to emulsify.Scrape down sides of bowl and add melted butter through the lid slowly, as you continue to blend until a thick consistency is achieved.
Serve Rosti piping hot, with poached eggs, wilted spinach and drizzled with the Simple Hollandaise.