In a large pan, sauté onion, garlic, and red pepper flakes in 2 tablespoons olive oil over medium heat until golden, 20–25 minutes. Remove from heat and combine with greens. In a medium bowl, combine eggs, ricotta, and half-and-half or cream; stir into greens and season with salt and pepper. Turn into a 2 1/2-quart casserole dish (or one of approximate size). Toss breadcrumbs with remaining 1 tablespoon olive oil; sprinkle over kale. Bake at 400˚ for 30 minutes. If the top isn’t golden and bubbly, broil for a minute or two.