Cheesy pasta casserole - Trois fois par jour

Ingredients

• 400g of penne
• 4 tablespoons butter
• 1 cup onion, finely chopped
• 1/4 cup flour
• 2 1/4 cups milk
• 1 cup of cooking cream (15% or 35%)
• 4 cups grated cheese of your choice (I like Kraft’s four-cheese Italiano mix)
• 1 cup cooked ham (or bacon), roughly chopped
• Salt and pepper, to taste