Saut onion in hot oil in a large nonstick skillet over medium-high heat 5 minutes or until tender.
Add squash, and cook 1 to 2 minutes or just until warm.
Remove from heat.
Toss spinach in a bowl with Blue Cheese Vinaigrette. Arrange baby spinach on a serving platter; top with squash mixture, cranberries, pecans, and bacon.