Preheat oven to 400 degrees F. Lightly oil a baking sheet or coat with nonstick spray.
In a small bowl, whisk together butter, olive oil, Parmesan, garlic, oregano, basil and salt; set aside.
Place croissant halves, cut side up, onto the prepared baking sheet and brush each croissant with half of the butter mixture. Place into oven and bake until golden brown and toasted, about 7-8 minutes.
Serve immediately, brushed with remaining butter mixture, and garnished with parsley, if desired.