Preheat your oven to 350°F (175°C). Grease a 9x13 inch baking dish.

In a large skillet over medium heat, cook the bacon until crispy. Remove the bacon, chop or crumble it, and set aside. Reserve about 2 tablespoons of bacon fat in the skillet.

In the same skillet with the reserved bacon fat, sauté the chopped onion until translucent, about 5 minutes. Add the minced garlic and cook for another minute until fragrant.

Spread the thawed diced potatoes evenly in the bottom of the prepared baking dish. Season with salt and pepper. Scatter the sautéed onion and garlic mixture over the potatoes, followed by the crumbled bacon.

In a large bowl, whisk together the eggs, milk, salt, pepper, and paprika (if using) until well combined. Stir in 1 1/2 cups of the shredded cheddar cheese.

Pour the egg mixture over the potato layer in the baking dish. Make sure the mixture is evenly distributed.

Bake in the preheated oven for 40-45 minutes, or until the eggs are set and the top is lightly golden.

Sprinkle the remaining 1/2 cup of cheddar cheese over the top of the casserole. Return to the oven for an additional 5 minutes, or until the cheese is melted and bubbly.

Let the casserole cool for a few minutes before slicing. Garnish with chopped green onions or chives before serving.