To make the cheese sauce, melt the butter in a saucepan. Stir in the flour and cook briefly. Gradually whisk in the milk and bring to a boil, stirring constantly. Remove from heat and stir in the cheese. Season with salt, pepper, and nutmeg.
Meanwhile, trim the ends of the zucchini and cut each into three equal pieces. Use a narrow glass to scoop out the inside of the zucchini. Set the zucchini insides aside for later use.
Combine the ground beef with roasted garlic, shredded cheddar, and an egg. Season the mixture with salt and pepper.
Fill the zucchini with the ground beef mixture. A freezer bag with a corner snipped, piping bag, or simple spoon will help get the job done.
To make the tomato sauce, finely chop the reserved zucchini insides and sauté them in olive oil. Add the onions and rosemary and sauté briefly. Add the diced tomatoes and bring to a boil.
Place the ground beef-stuffed zucchini upright in the hot tomato sauce and top each zucchini piece with a dollop of cheese sauce.
Bake for 30 minutes, let briefly cool, and then enjoy!
Notes
Tip: To roast the garlic, wrap the head of garlic in aluminum foil and bake in the oven until soft. This gives the ground beef a special aroma.