Preheat oven to 425 degrees with rack in the center.
In a large frying pan, cook bacon until brown and crispy.
Remove from pan and drain on paper towel.
Reserve 1 teaspoon bacon fat and set aside to cool. Crumble bacon.
Toss cubes with garlic salt, cinnamon, ginger, ground sea salt, black pepper, and bacon fat.
Spread cubes on a cookie sheet in a single layer.
Roast in oven for about 30-35 minutes until cooked through and golden brown.
Turn once with tongs about halfway through cooking time for even browning.
Remove yams from oven and let cool.
Whisk together extra-virgin olive oil, balsamic vinegar, shallot, and Grey Poupon mustard.
Add salt and freshly ground pepper to taste.
Place baby spinach in a large bowl.
Top with bacon crumbles, roasted yams, Gruyere, pomegranate seeds, and walnuts.
Toss with vinaigrette.