Preheat your oven to 350°F (175°C). Spread the walnuts on a baking sheet in a single layer and toast them for about 8-10 minutes, stirring halfway through. Keep a close eye to avoid burning.
In a small bowl or jar, combine the olive oil, apple cider vinegar, honey, salt, and pepper. Whisk or shake vigorously until the dressing emulsifies into a smooth, golden mixture. Adjust seasoning as needed.
Core the apple and slice it thinly to ensure every bite includes a crisp, juicy element.
In a large mixing bowl, add the fresh spinach leaves, sliced apple, toasted walnuts, dried cranberries, and crumbled feta cheese. Drizzle the dressing over the salad and toss gently but thoroughly to coat every ingredient.
Transfer the salad to a serving bowl or plate and enjoy immediately for the freshest flavors and textures.