White sauce: add the heavy cream, garlic powder, onion powder, dried thyme, salt and pepper to a medium size jug and use a mini whisk to stir and combine. Then place in the fridge until 10 - 15 minutes before adding to the recipe.
Potatoes: use a vegetable peeler to peel the potato skins and discard. Then use a mandolin or knife to thinly slice the potatoes into slices.
Grease: use a little bit of olive oil and a folded piece of paper towel and grease the base and sides of the slow cooker insert.
Layer: make a layer of the potato slices on the base of the slow cooker. Then top this layer with a layer of the diced ham. Repeat the layers till you have used up all of the potatoes and ham, finishing with a layer of potatoes on top.
Cook: now place the lid on the slow cooker. Cook the scalloped potatoes and ham for 3 hours on high heat or 7 hours on low heat to start with. 10-15 minutes before this time is reached, removed the cream sauce from the fridge. At the 3 hour mark (high) or 7 hour mark (low) remove the lid from the slow cooker and pour in the creamy sauce. Then put the lid back on for 30 minutes. Next at the 3 ½ hour (high) or 7 ½ hour (low) heat, remove the lid and sprinkle the grated cheese over the top of the potatoes. Put the lid back on and let the cheese melt and cook for a final 15 - 30 minutes.
To serve: once the scalloped potatoes have finished cooking, remove the lid and let them sit for 10 - 15 minutes to allow the sauce to thicken. Then sprinkle finely chopped parsley over the top of the cheese. Use a wooden spoon to portion onto plates.