Begin by boiling a large pot of salted water over medium-high heat. Once the water reaches a rolling boil, add the cheese tortellini and cook according to the package instructions for about 3–5 minutes until they float to the surface and become tender. Drain the tortellini and set aside.

In a large skillet, heat 1 tablespoon of olive oil over medium heat. Once hot, add the sliced beef sirloin to the pan and cook for about 5 minutes, stirring occasionally until browned. Remove and set aside.

In the same skillet, add an additional tablespoon of olive oil if necessary, then add the chopped green bell pepper, diced onion, and minced garlic. Sauté over medium heat for about 5–7 minutes until softened and fragrant. Remove from heat and set aside with the beef.

In a separate saucepan, melt 2 tablespoons of butter over medium heat. Whisk in 2 tablespoons of flour for about 1 minute to create a roux.

Gradually whisk in 2 cups of whole milk, cooking until thickened for about 3–4 minutes. The sauce should coat the back of a spoon.

Reduce heat to low and stir in 1 cup of shredded provolone cheese and ½ cup of grated Parmesan cheese until melted and smooth. Season with salt and pepper.

Fold the cooked tortellini, sautéed beef, and vegetables into the creamy cheese sauce until well-coated and heated through, about 2-3 minutes.

Transfer to a large serving dish. Garnish with chopped parsley or additional Parmesan cheese if desired. Serve hot.