Line a baking sheet with foil. Spray foil with non stick spray. Preheat oven to 400
Remove paper skin from onion and cut in halve, keeping root end intact
Sprinkle onions with salt. Heat a film of olive oil in skillet that will hold onions in one layer until hot. Place onions cut side down in oil and cook on medium until surface is golden about 10 minutes
Turn over, add butter and a sprinkle of pepper, cover, reduce heat to low and cook until onion is just tender but still firm enough to hold its shape, about 10 to 15 minutes depending on size of onion
When cool enough to handle, seperate petals and place on prepared pan
Divide cheese into petal centers
Add any toppings. I used half bacon and half pepperoni. Place in the oven and cook just until cheese melts. The onion should keep its shape. Thisn will take about 5 minutes
Transfer to plate and serve
