For vinaigrette, add vinegar, maple syrup, olive oil, salt, pepper, and apple pie spice to a glass jar with a tight-fitting lid. Cover and shake to combine.

Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned. Drain bacon slices on paper towels.

Combine mixed greens with sliced apples and onion in a large bowl. Top with pecans and havarti cheese.