Step 1: Cook the Potatoes and Garlic

1. In a large pot, add diced potatoes and garlic cloves. Cover with cold water and add a pinch of salt.
2. Bring to a boil over medium-high heat, then reduce to a simmer.
3. Cook for 15-20 minutes, or until the potatoes are fork-tender.
4. Drain the potatoes and garlic well, then return them to the pot.

Step 2: Mash the Potatoes

1. Add 1/4 cup of butter to the pot with the hot potatoes and garlic.
2. Mash the potatoes and garlic together until smooth and creamy.
3. Stir in the milk, heavy cream, and sour cream. Mix until well combined.
4. Season with salt and pepper to taste.

Step 3: Add Bacon and Chives

1. Fold in the crumbled bacon and chopped chives.
2. Mix well to ensure the ingredients are evenly distributed.

Step 4: Prepare the Cheddar Topping

1. Preheat your oven to 400°F (200°C).
2. Transfer the mashed potatoes to a greased baking dish.
3. Sprinkle the top with half of the shredded cheddar cheese.
4. Add a layer of Parmesan cheese, if using.
5. Top with the remaining cheddar cheese and a sprinkle of smoked paprika.

Step 5: Bake Until Golden and Crispy

1. Place the baking dish in the preheated oven.
2. Bake for 15-20 minutes, or until the cheese is melted and bubbly, and the crust is golden brown.
3. Remove from the oven and let it rest for 5 minutes before serving.