Preheat oven to 350°F (180°C). Line a rimmed baking sheet with parchment paper. In a small saucepan heat sugar, cayenne, nutmeg, 2 tsp (10 mL) water, honey and salt over medium-low heat, without stirring, until sugar dissolves. Remove from heat and set aside.
If transporting to potluck, in a small bowl, whisk egg white until foamy, add walnuts and gently toss to coat. Transfer nuts to sugar mixture and stir to coat. Arrange nuts in a single layer on prepared baking sheet and bake for 10 min. Let nuts cool completely before storing in an airtight container.
In a reasealable container, combine garlic paste, yogourt, lemon juice and pepper. In a large bowl, toss together kale, romaine, celery and apple. Cover with plastic wrap before transporting.
To serve, add dressing to salad and toss well. Top with spiced walnuts just before serving.