Pour the completed sauce into the serving container and store it in a warm place until used. You can also place the serving container into a shallow bowl of hot water to help keep it warm. Use within the hour.
Cook the bacon in a skillet over medium heat until golden brown and crispy. Place on a paper towel to drain grease. Set aside.
Remove all of the bacon grease from the skillet. Heat the butter in the same skillet over medium-high heat. Add the mushrooms and leave undisturbed for 3 minutes then toss and continue to cook until golden brown and caramelized, about 2-3 minutes. Add the shallot and cook, stirring often, for 1 minute. Add the garlic and cook, stirring constantly, for 1 minute. Remove from the heat and season with sea salt and freshly cracked pepper, to taste, along with a squeeze of lemon juice. Toss to coat evenly. Set aside.
Heat 1 ½ inches of water and 1 teaspoon of white vinegar in a small saucepan and bring to a simmer.
Break 1 egg into a small ramekin. Once the small saucepan of water is at a simmer, stir the water with the bottom of your slotted spoon clockwise to make a swirling motion in the water. Quickly and carefully slide the egg into the water.
Cover and turn stove off. Poach until whites are firm and yolks are still runny, 3 minutes and 40 seconds. Remove the egg using a slotted spoon and drain a bit over the pan.
While the egg is cooking, toast the English muffin half then butter it, if desired.
Add slices of bacon followed by some of the caramelized mushrooms. Top with the drained poached egg then pour some hollandaise sauce on top.
Sprinkle with some finely minced chives. Serve immediately. Enjoy!