Preheat your oven to 400°F (200°C). Spread the frozen hash browns evenly on a baking sheet and bake for about 20 minutes, or until golden brown and crispy.

While the hash browns are baking, heat a skillet over medium-high heat and add olive oil. Add the bacon strips and cook until crispy, about 5-7 minutes. Transfer to a paper towel-lined plate and crumble once cooled.

In the same skillet, crack in the eggs and poach them for 3-4 minutes until whites are set and yolks are runny. Season with salt and black pepper. Use a slotted spoon to remove and set aside.

Prepare the hollandaise sauce using a double boiler or heatproof bowl over simmering water. Whisk egg yolks, Dijon mustard, and white wine vinegar until pale and foamy. Gradually drizzle in melted butter while whisking continuously until thick.

Once hash browns are ready, place them on a serving plate. Layer on the poached eggs, followed by crumbled bacon, cheddar, and mozzarella. Spoon warm gravy over the top to melt the cheeses.

Finish with a drizzle of hollandaise sauce and serve immediately while hot.