Pecans: Melt the butter in a large skillet over medium-low heat. Stir in all the spices and the pecans. Stir and toast the pecans for about 5 minutes. Transfer them to a plate to cool.
Salad: Whisk together the Dijon mustard, shallots, and balsamic vinegar in a small bowl. Drizzle in the olive oil in a continuous stream, whisking to emulsify. Season with a pinch of sugar, and salt and pepper, to taste.
Add the spinach to a large serving bowl. Toss the greens with the prepared dressing, the bacon, blue cheese, cherry tomatoes and spiced pecans.