In a medium bowl, whisk together the Dijon mustard, honey, and apple cider vinegar until well combined and the honey dissolves completely. Add the mashed blue cheese and whisk vigorously until it's fully incorporated and the dressing has a creamy, emulsified appearance. Season with salt, pepper, and garlic powder, then slowly drizzle in the extra virgin olive oil while whisking constantly to create a smooth, cohesive vinaigrette. I prefer to mash the blue cheese separately before adding it—this ensures it dissolves evenly rather than creating clumpy pockets in the dressing.

While the dressing rests, prep all the salad toppings to ensure they're ready for assembly. Thinly slice the red onion into half-moons and place in a small bowl. Halve the cherry tomatoes lengthwise and set aside. Crumble the cold blue cheese while it's still chilled for better texture and separation. Roughly chop or leave the walnuts whole depending on preference. Keep the pickled radish and croutons in their containers, ready to add. I like to slice my onions just before assembly so they stay crisp and don't begin to soften.

Place the 6 cups of spring mix into a large serving bowl or divide among individual plates. Layer the prepared toppings over the greens in this order: red onion, cherry tomatoes, crumbled blue cheese, walnuts, pickled radish, and croutons. This layering approach helps distribute flavors evenly and keeps the croutons on top where they'll stay crunchier and less likely to absorb dressing immediately.

Give the dressing from Step 1 a quick whisk to recombine if any separation has occurred, then drizzle it over the assembled salad just before serving. Use about 3-4 tablespoons of dressing per serving, depending on preference—you want the salad lightly coated, not drenched. Serve immediately while the greens are still crisp and the croutons maintain their crunch.