To caramelize onions, heat a wide, sauté pan over medium high heat. Add olive oil and heat. Then add onion slices and ½ teaspoon salt and stir. Lower heat to medium low and cook 40-60 minutes, stirring occasionally, until onions are golden brown. Add a little water to the pan if it the onions start to dry out. The add honey and cook for 1 more minute. Set aside.
Pre-heat oven to 375 degrees F. Grease a 13 x 9 inch pan with butter or oil.
In a large bowl, whisk together eggs, vegetable oil, Panko breadcrumbs, Sriracha, 1 ½ teaspoons salt and pepper.
Grate the potatoes with a hand grater or food processor and squeeze out excess moisture with towels. Add potatoes and caramelized onions to the egg mixture and mix until combined.
Pour into the 9 x 13 inch pan and bake, uncovered, for 60-75 minutes until golden brown and a knife inserted comes out clean. Let cool 10 minutes before eating.
Garnish with scallions if desired.
Reheats well in the oven, but it doesn't freeze so great.