On a lightly floured surface, knead dough together. Roll out into a 7-in. circle. Place on greased 7-1/2-in. pizza pan or baking sheet. Brush with oil. Top with onion slices. Sprinkle with Italian seasoning and Parmesan cheese.
Bake at 350° for 28-32 minutes or until golden brown.
In a small bowl, combine the butter and garlic salt; brush over warm foccacia. Cool for 10 minutes on a wire rack before cutting.