Preheat your oven to 350°F (175°C).
In a large pot, boil water and add the diced potatoes. Cook for about 10-15 minutes, or until fork-tender. Drain and set aside.
In the same pot, melt the butter over medium heat. Add the chopped onion and garlic, sautéing until the onions are translucent (about 5 minutes).
In a large mixing bowl, combine the heavy cream, chicken broth, paprika, salt, black pepper, thyme, and cayenne pepper. Whisk together until well blended.
Layer the cooked potatoes in the baking dish. Pour the cream mixture over the potatoes, ensuring they are evenly coated.
Sprinkle the shredded cheddar cheese on top of the potato mixture.
Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes.
After 30 minutes, remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and slightly golden.
Remove from the oven and let it cool for a few minutes. Garnish with fresh parsley if desired before serving.