In a small bowl, whisk together cheese, oil, vinegar, mustard, garlic, salt and pepper.
Place barley in a pot and cover with water about 4 inches (10 cm) above barley. Bring to a boil. Reduce heat; cover and simmer gently for about 30 minutes or until tender but firm. Drain well and set aside.
Preheat oven to 400F (200 C).
In a large bowl, toss squash with oil, thyme and half each of the salt and pepper. Spread onto parchment paper lined baking sheet and roast for about 30 minutes or until tender and golden. Return squash to bowl and stir in barley, tomatoes, arugula, candied nuts, if using and cheese. Drizzle with dressing and toss well to combine.
In a small skillet, heat 1/2 cup (125 mL) sliced almonds with 3 tbsp (45 mL) granulated sugar and 1 tbsp (15 mL) butter over medium low heat. Cook stirring for about 8 minutes or until almonds are golden. Spread onto plate and let cool completely before using.