1. Make the hollandaise sauce: Heat a pan containing 2 inches of water over low heat until it is barely simmering. Separate 4 of the eggs and place yolks in a heatproof bowl (store egg whites in the refrigerator in a covered container for another use). Place yolks over barely simmering water, making sure the bowl does not touch the water and whisk constantly while slowly adding the lemon juice. Continue whisking until thick, 2-3 minutes.
2. Slowly whisk the melted butter into the egg mixture, continually whisking until sauce is smooth
and thick. Remove from heat and season with salt (in moderation) and pepper. Cover and set aside to keep warm.
3. Heat oil in a skillet over medium-high heat and add spinach by handfuls, adding more as spinach wilts (add 1 tablespoon water, if necessary). Sauté until all the spinach has wilted, about 3 minutes. Season to taste with salt (in moderation) and pepper and remove the pan from heat. Cover and set aside.
4. Toast the English muffin halves. Bring a pot of salted water to a boil. With a large spoon, stir the water in a circular motion. Crack the eggs, one at a time, into a small cup and carefully slide each egg into the center of the whirlpool. For a soft poached egg, gently simmer for about 3 minutes. For a firmer egg, gently simmer for 4 minutes.
5. Remove the eggs with a slotted spoon and place on a paper towel to drain. Divide the spinach evenly among the English muffin halves and top with poached eggs and hollandaise sauce. Garnish with cracked black pepper.
Per serving: 603 calories, 53g fat, 26g saturated fat, 523mg cholesterol, 320mg sodium, 15g carbohydrate, 1g fiber, 1g sugar, 18g protein