Preheat your oven to 400°F (200°C). Spread the frozen hash browns evenly on a baking sheet, ensuring they are not crowded. Bake for about 20 minutes, flipping halfway through, until they turn golden brown and crispy.

While the hash browns are baking, heat a skillet over medium-high heat and add a splash of olive oil. Add the bacon strips and cook for 6-8 minutes or until crispy, turning occasionally. Once cooked, remove the bacon and let it drain on paper towels. Crumble it into bite-sized pieces for topping.

In a medium saucepan, bring water to a gentle simmer and add a splash of white wine vinegar. Carefully crack the eggs into the simmering water, ensuring they don't touch each other. Poach the eggs for 3-4 minutes until the whites are set, but the yolks remain runny.

Set up a double boiler with simmering water in the bottom pot and a heatproof bowl on top. In the bowl, whisk together egg yolks, Dijon mustard, and white wine vinegar until combined. Gradually drizzle in the melted unsalted butter while whisking continuously.

Once the hash browns are perfectly crispy, place them on serving plates as the base. Top each with poached eggs, sprinkling shredded cheddar and mozzarella cheese over the warm potatoes. Drizzle gravy on top before adding crumbled bacon, and finish with hollandaise sauce.