Dissolve honey in the warm water in a large bowl, then sprinkle yeast over the top. Let stand for 5 minutes until the yeast softens and begins to foam. Stir in 1 tablespoon of salt, 1 tablespoon olive oil, onions, and 5 cups of flour until the dough comes together. Knead on a well floured surface until smooth and elastic, about 5 minutes. Lightly oil a large bowl, place the dough in the bowl and turn to coat with oil. Cover with a damp cloth and let rise in a warm place until doubled in volume, about 20 minutes.
Preheat oven to 415 degrees F (215 degrees C).
Place dough onto oiled baking sheet, and flatten to cover the whole sheet evenly. Use the tips of your fingers to make indentations all over the dough spaced about 1 inch apart. Drizzle the focaccia with 3 tablespoons olive oil, then sprinkle rosemary, Parmesan cheese, and remaining 1 tablespoon of kosher salt over the top. Let rise for 10 minutes
Bake in preheated oven 20 minutes until golden brown.