Chop tomatoes, mushrooms, spinach, red onions, and bell peppers into small pieces. Place them in a large bowl.
Fry bacon until crispy, then chop it into small pieces. Set aside.
In a separate bowl, whisk together oil, vinegar, sugar, mustard, and poppy seeds to make the dressing.
Add chopped bacon, croutons, dried cranberries, hard-boiled eggs, and shredded cheese to the vegetable bowl.
Drizzle the poppyseed dressing over the ingredients and gently toss until well-coated.
Taste and adjust with salt, pepper, or extra dressing as desired.