Step 1

Heat the oil over medium-high heat in a large pan.Add the minced beef and stir breaking the clumps constantly until the meat has changed color and all the released liquid has evaporated.Continue stirring, until the meat is lightly browned (about 5 minutes)

Step 2

Add the onion and the garlic, and cook, stirring until the onion turns translucent. Add tomato and bell pepper and cook stirring for a couple of minutes.Add the tomato sauce and stir to mix well. Season with salt and pepper to taste.Cover and simmer over low heat for 10 minutes, or until almost all the liquid has evaporated. Mix in the parsley and set aside.In the meantime, heat the oven to 350 ºF [175 ºC].

Step 3

In a medium saucepan, heat butter over medium-low heat.Once the butter has melted, add the flour all at once, stirring vigorously to mix with the butter without clumping. Cook, stirring until the flour changes colors (about 2-3 minutes).Slowly add the milk, stirring vigorously to prevent the mixture from becoming clumpy (see notes above the recipe). Once it is thoroughly mixed, stir slowly but continuously for another 2-3 minutes until it has thickened a bit (like drinkable yogurt). Season with salt and pepper to taste.Remove from the heat and continue stirring until it cools to room temperature, it'll thicken more as it cools. Set aside.

Step 4

Pour half of the bechamel in a lasagna baking pan and spread evenly.Fill the uncooked cannelloni with the meat filling using a little spoon.Place the cannelloni on the baking pan and bathe with the rest of the bechamel, covering them evenly. Cover the pan tightly with aluminum foil.

Step 5

Bake the cannelloni for 30 minutes.Uncover, spread the mozzarella on top, and cook in the broiler until it is bubbly and golden brown in spots.

Step 6

Remove from the oven, sprinkle with minced parsley, and serve. See serving suggestions above the recipe.