Preheat oven to 350°.
In a large microwavable bowl, place cheese cubes, butter & milk. Microwave on high 8-10 minutes and stir with a whisk. Microwave another 4 minutes and stir. Repeat until completely melted and mixture is smooth.
Cook macaroni in boiling salted water 3 minutes less than directed on package (macaroni should still be slightly firm as it will continue to cook in the oven).
Mix together the spinach, Pico, cooked hamburger and shredded cheese and cooked macaroni. Stir in cheese sauce and mix well. Pour into a 15 x 10 glass baking dish sprayed with Pam.
Cover dish with foil, bake 30 minutes. Uncover, sprinkle with crumbled bacon and bread crumbs evenly over top. Bake 5 minutes longer or until top is lightly browned. Cool at least 10 minutes before serving.
**Note: You can use any ground meat you like, I've used beef, chorizo, turkey... whatever you like. I've also used the french fried onions instead of bread crumbs (in the photo). Mix it up with your favs! :-)