Fill a small pot with 1 inch of water. Bring to a boil over high heat, then reduce to a simmer over low heat.

While the water is coming to a boil, melt the butter in a small saucepan over medium heat or melt it in the microwave. Let cool slightly. (It should be very warm, but not steaming hot.)

In a mixing bowl large enough to sit on top of the pot without touching the water, whisk the egg yolks until they are pale yellow, about 1 minute. Whisk in the lemon juice, salt, and paprika.

When the water is simmering, place the bowl with the egg yolk mixture over the top. While whisking vigorously, slowly drizzle the hot butter into the egg mixture, starting with a few drops at a time, increasing to a thin stream.

Once the butter has been added, cook for 3 to 5 more minutes while whisking frequently until the mixture is creamy, thickened, and coats the back of a spoon. Remove the bowl from the heat. Cover and set aside.

Fill a large pot with about 2 inches of water. Bring to a simmer over medium-high heat, then reduce the heat enough to keep the water hot and steaming but not vigorously bubbling. Stir in the vinegar.

Crack one egg into a small ramekin. Gently drop an egg into the center of the water. Let it cook for 1 minute, then stir the water so that the egg floats up from the bottom of the pot. (If your pan is large enough you can add 2 or 3 eggs a time, just be sure there is plenty of space between each one, and stir the water very gently so you don’t break the egg yolks.)

Cook for 3 to 5 minutes, depending on the desired doneness. (A longer cook time will result in a firmer white and less runny yolk.) Remove each egg with a slotted spoon and transfer it to a paper towel-lined plate. Repeat with remaining eggs.

While the eggs are poaching, heat a large skillet over medium heat. Add the olive oil and garlic and cook for 1 minute. Add half of the spinach and stir, cooking for about 1 minute, until slightly wilted. Add the remaining spinach and stir, cooking for another 1 to 2 minutes, until all is wilted. Season with the salt and pepper. Remove from the heat and cover to keep warm if the eggs are still cooking..

To serve, divide the spinach evenly over the toasted English muffin halves. Place a poached egg on top of the spinach, and spoon the Hollandaise sauce over each egg. Garnish with chives and serve immediately.