Preheat oven to 425 degrees F. Add olive oil and butter to a large cast iron skillet/oven safe pan over medium heat. Add sliced red onions and cook until onions begin to soften, about 3-5 minutes.
Add to the pan and brown on both sides. Add jasmine rice and continue to saute in pan until rice becomes toasted/golden. Add chicken broth, milk, frozen corn, and frozen broccoli and mix together.