Preheat the oven to 400°F (204°C). Toast the walnuts in the oven for 8-9 minutes, watching closely to prevent burning. Once cooled, roughly chop them.

To prepare the salad, first layer the arugula as the base, followed by the roasted beets, sliced apples, cheese, and finally, the toasted walnuts. Drizzle your dressing over the top before serving.

Roasting the beets can be done up to three days ahead. Store them in a lidded container in the refrigerator. Toasted walnuts should be kept at room temperature.

To make the dressing, combine olive oil, apple cider vinegar, maple syrup, salt, and Dijon mustard (if using) in a jar. Shake well to emulsify.

The dressing can also be prepared up to three days in advance, storing it at room temperature for up to three days or in the fridge for a week.