In a saucepan, heat oil and sauté garlic then beef for one minute or until beef changes in color. Add tomato sauce and simmer for 2 minutes. Season with salt and pepper. Simmer covered for 10 minutes over low heat. Fold in macaroni. Transfer to an ovenproof dish.
Make the white sauce by melting the butter in a saucepan. Add flour while whisking and cook for 1 minute over medium heat.
Add cream and half of the cheese while continuously whisking the mixture. Simmer for 2 minutes over low heat or until thick. Spread on top of macaroni mixture.
Top with remaining cheese and bake in the oven for 10 minutes or until cheese has melted and top layer has browned slightly.