Preheat the oven to 350 degrees F (175 degrees C). Line a baking sheet with parchment paper.

Place 3 tablespoons honey in a microwave-safe bowl. Microwave on Medium until honey liquefies, about 30 to 45 seconds. Add walnuts and stir to coat. Spread in one layer onto the prepared baking sheet and bake in the preheated oven until nuts have darkened slightly, 8 to 10 minutes. Remove from oven, sprinkle with 1/2 tablespoon sugar and 1/2 teaspoon salt, and stir to coat. Allow to cool.

Combine olive oil, blackberry jam, balsamic vinegar, orange juice, Dijon mustard, 2 teaspoons honey, basil, salt, and pepper in a lidded jar. Shake until vinaigrette is well combined and chill in the refrigerator until serving.

Combine spinach, sweet apple, Granny Smith apple, cucumber, bell peppers, green onions, feta, and cooled walnuts in a large bowl. Toss to combine. Carefully mix in blackberries. Drizzle with vinaigrette and toss.