Begin by washing all the fresh produce thoroughly under cold water. Pat them dry with a clean kitchen towel. Chop the romaine lettuce, baby spinach, cucumber, and cherry tomatoes into bite-sized pieces. Slice the avocado and hard-boiled eggs. Cook the bacon until crispy in a skillet over medium heat, allowing about 6-8 minutes, and then crumble it into smaller pieces for easy mixing.

In a large salad bowl, combine the chopped romaine lettuce and baby spinach as your vibrant base for the Cobb Salad. Ensure the greens are distributed evenly to create a colorful display. Next, add in the grilled chicken breast pieces, crispy bacon bits, and chopped hard-boiled eggs, layering these protein-packed ingredients generously over the leafy greens for a nutritious boost.

Fold in the diced cucumber, halved cherry tomatoes, and red onion into the salad bowl. These ingredients not only add a delightful crunch but also enhance the visual appeal of your Cobb Salad with vibrant colors. Toss gently to avoid breaking down the avocado while maintaining the integrity of the salad.

In a small bowl or a jar with a lid, whisk together about 1/3 cup of olive oil, 1/4 cup of red wine vinegar, and a tablespoon of Dijon mustard. Add a pinch of salt and pepper to taste. If using a jar, close the lid tightly and shake vigorously until all ingredients are emulsified.

Just before serving, drizzle the homemade dressing over the Cobb Salad, ensuring even coverage as you pour. Gently toss the salad with tongs or two large forks to mix the ingredients while keeping them intact.

Transfer the tossed Cobb Salad to individual plates or serve it family-style in the large bowl. For an attractive presentation, consider adding extra crumbled feta cheese and a few slices of avocado on top.