Preheat the oven to 350°F.
Place the chopped bacon in a large skillet over medium-high heat.
Cook the bacon until browned and crispy.
Using a slotted spoon, transfer the cooked bacon pieces to a paper towel-lined plate and set aside.
Add the lean ground beef to the same skillet.
Cook the ground beef over medium-high heat, breaking it apart as it cooks.
Once the ground beef is fully cooked, drain the grease from the skillet.
Add the minced garlic to the cooked ground beef.
Stir well and continue cooking for 2 to 3 minutes.
Remove the skillet from the heat.
Add the instant rice to the skillet and stir until evenly combined with the beef mixture.
Add the condensed cheddar soup, milk, and ranch dressing mix.
Stir until the mixture is fully combined and evenly coated.
Add 1 cup of the shredded cheese, 1 cup of the chopped green onions, and approximately two-thirds of the cooked bacon pieces.
Stir until all ingredients are thoroughly combined.
Grease a 9x13-inch baking dish well with nonstick cooking spray.
Transfer the beef and rice mixture to the prepared baking dish.
Spread the mixture evenly in the dish.
Cover the baking dish tightly with aluminum foil.
Bake for 40 minutes.
Remove the baking dish from the oven.
Carefully remove the aluminum foil.
Sprinkle the remaining 2 cups of shredded cheese evenly over the casserole.
Sprinkle the remaining cooked bacon pieces over the cheese.
Return the baking dish to the oven, uncovered.
Bake for an additional 5 to 10 minutes, or until the casserole is bubbling and the cheese is fully melted.
Remove the casserole from the oven.
Allow it to rest for a few minutes before serving.
Sprinkle the remaining 1/4 cup of chopped green onions over the top.
Serve warm.