Try this simple scalloped potato recipe with caramelized onions.
Spray a 2-quart baking dish with non-stick cooking spray and set aside.
Heat 2 tablespoons butter in skillet; add breadcrumbs and stir to coat. Remove buttered breadcrumbs to small plate and set aside.
Heat remaining butter in skillet over medium-high heat; add onion. Sauté until onion is coated with butter; reduce heat to medium and cook until lightly browned and tender (about 10 minutes).
Remove skillet from heat; add potatoes to caramelized onion and toss to mix. Pour potato mixture into baking dish; set aside.
Add half and half, salt, and pepper to skillet and cook until milk is hot but not boiling. Pour over potato mixture.
Cover baking dish with foil and bake at 375 degrees F for 40 minutes; remove foil and sprinkle buttered breadcrumbs evenly over potatoes.
Return to oven for additional 15 minutes, or until crumbs begin to brown.