You will need 1 small pot for eggs, 1 medium pot for potatoes, and 1 sheet pan or skillet for bacon (depending on how you want to cook it). Optional: metal cooling rack that fits into sheet pan.
Make the potatoes by peeling them, then cutting into ¾ inch pieces. Cover them with cold water + 1 teaspoon salt and then bring to a boil. Let them boil for about 5 minutes or until a fork slips in and out of the potato very easily. Then drain the potatoes and gently rinse with cold water or place into an ice water bowl to stop the cooking (you don't want them to turn to much).
Hard boil the eggs by covering them with cold water and bringing them to a boil. As soon as the water starts to boil, turn off the heat, cover the pot and let sit for 7 minutes. Remove the eggs and run under cold water. Then put in the fridge to fully cool.
The Bacon! Cook the bacon using whatever method you prefer so that it is crispy. I like the lazy mans version in the oven. Turn the oven to 400 degrees F and cover a pan with aluminum foil, then place a metal cooking rack on top of the aluminum. Place the bacon on the rack and then cook in the oven for 15 minutes or until the bacon is crispy, but not burned. Drain on a paper towel and then let cool to crumble.
While the eggs, potatoes, and bacon are cooking, you can dice the carrots, finely slice the scallions, and rough chop the spinach, just so there aren't any really large leaves.
When the eggs are cooled, peel the and then dice into small pieces. Set aside or store in the fridge.
To make the dressing ahead, in a small mixing bowl add the mayonnaise and the mustard. Whisk together. set aside or store in fridge until ready to mix into the salad.