Bring a medium pot of hot water to a boil over high heat.
Add the eggs, gently with a spoon, into the boiling water. Set your timer for 10 minutes.
While the eggs are cooking, prepare the homemade poppy seed dressing (link in post and in notes below). Slice your mushrooms, and grate your cheese if necessary.
When the eggs are done cooking, drain off the boiling water and add to a bowl of ice cold water. Hold the eggs under a tap running with cold water as you peel them. I like to hit my eggs with the back of a spoon and gently peel the shell off. Set the eggs aside to cool further.
Add the spinach to a large serving or salad bowl, top with the mushrooms, crumbled bacon (if using), and shredded mozzarella.
Slice the eggs and top the salad with them. Serve with homemade poppy seed dressing on the side, or drizzle on the salad if you are sure there will be no leftovers. ⅔