Preheat oven to 425 degrees. Line a rimmed baking sheet with foil.
In a medium frying pan, heat the pesto, saute the onion for 2-3 minutes. Add the green beans and cook for additional 3-4 minutes.
Add in the lemon zest, garlic powder, salt, and pepper, shallots, bacon bits (optional), and mix together.
Spread the green bean mixture on an even layer on the baking sheet. Bake for 15 minutes or until tender.