Make Cauliflower Patties: Grate cauliflower on a box grater until shredded. Add to a medium bowl and crack in an egg. Add cheddar and cornstarch and season with salt.
In a large skillet over medium-high heat, heat oil. Add spoonfuls of cauliflower mixture and shape into patties. Cook until brown and crispy, 5 minutes, then flip and cook 5 minutes more.
Poach Eggs: Bring a saucepan of water to a boil, then reduce to a low simmer. Create a vortex by stirring the water, then drop in an egg. Let cook 3 minutes, then transfer with a slotted spoon to a paper towel. Repeat with remaining egg.
Discard all but two inches of water and bring to a low simmer. Add water over saucepan to create a double boiler and add egg yolks. Add lemon juice and whisk until combined, then stir in butter in a steady stream, whisking constantly, until combined. Season with cayenne and salt.
Serve cauliflower hash brown patties topped with Canadian bacon, poached eggs and hollandaise. Garnish with paprika and chives.