Add olive oil to a large skillet and heat until oil is shimmering. Add onions and celery. Saute for 5 minutes, or until onions are translucent and celery is softened.
Preheat oven to 350 degrees F.
While vegetables are sautéing, add bread cubes to a very large bowl. Add parsley and salt. Mix eggs in with the broth until well blended. Slowly add broth, lemon juice, and butter while stirring.
Place in 4 qt casserole dish (or 11 x 13'). Add lid or cover with foil (spray the underside of the foil with cooking spray to keep the stuffing from sticking). Bake covered for 30 minutes. Remove from the oven, stir stuffing, and return to oven uncovered. Bake for 20 minutes longer.
If your bread cubes are unseasoned, season with 2 tsp ground sage and 2 tsp dry thyme.