Bring a large pot of water to a boil, then blanch the broccoli florets for 2 minutes until vibrant green and slightly tender. Immediately transfer them to an ice water bath to stop the cooking and preserve their color. Drain well and set aside.
In a skillet over medium heat, cook chopped bacon until crispy, about 5-7 minutes. Use a slotted spoon to remove the bacon bits and drain on paper towels. Leave the rendered fat in the skillet.
Add diced onion to the same skillet with bacon fat and sauté until golden and fragrant, about 5 minutes. Let the onions cool slightly before mixing.
In a large mixing bowl, combine the blanched broccoli, sautéed onions, and crispy bacon bits. Mix gently to distribute evenly.
Stir in the can of cream of mushroom soup, shredded cheddar cheese, and a splash of milk if desired for extra creaminess. Season with salt, pepper, and smoked paprika to taste. Mix until everything is well coated and combined.
Transfer the mixture into a greased 9x13 inch baking dish, spreading it out evenly.
In a small bowl, toss breadcrumbs with melted butter and dried thyme or paprika if using. Sprinkle the topping evenly over the casserole.
Bake in a preheated oven at 180°C (350°F), uncovered, for 25-30 minutes until the top is golden brown and bubbling around the edges.
Once done, remove from the oven and let rest for 5 minutes to allow the casserole to set. The cheese should be bubbling and the breadcrumb topping crispy and golden.
Serve hot, garnished with extra cheese or herbs if desired, and enjoy the comforting, cheesy goodness with crispy topping and tender broccoli.
