Bring a pot of water to a boil. Add a teaspoon of salt and a pinch of sugar.

Use a fork to poke holes in the potatoes. Add them to the pot and cook until they are soft but not mushy. You should be able to run a fork through them but they should not fall apart.

Drain the potatoes and let cool. Peel the potatoes and slice them into rounds.

Layer the potato slices on the bottom of a  9x13 inch casserole dish.

Preheat the oven to 350 degrees F.

Drain the sauerkraut and evenly distribute it over the potatoes.

In a separate bowl, add half of the sour cream, the heavy cream, 2 eggs, the thyme leaves and 1/3 of the grated gouda cheese. Season with kosher salt, pepper and a pinch of nutmeg.

Pour the mixture evenly over the sauerkraut in the casserole dish. Use a rubber spatula to spread it out.

Wash and dry the apple. Slice the apple into rings. Use a small paring knife to cut out the seeds and core from each ring.

Lay the apple slices evenly over the top of the casserole.

Add the remaining sour cream and egg to the bowl and whisk together. Season with kosher salt, pepper and a pinch of nutmeg.

Brush the mixture evenly over the top of the apples.

Sprinkle the rest of the shredded Gouda cheese evenly over the top.

Place in oven and bake for 45 minutes.