In a large saucepan, cook rotini according to package directions. Drain and set aside in the strainer.

Meanwhile, heat the olive oil in the large saucepan. Once hot, add onion and garlic. Cook over medium heat for 3 minutes. Add broccoli, mushrooms, salt, and ½ teaspoon pepper.

Cook until softened, approximately 5-8 minutes. Remove from pan, spooning into strainer, on top of noodles.

Add butter to the saucepan. Melt over medium-low heat. Once fully melted, stir in flour, preferably with a whisk. Continue to whisk as the flour browns slightly.

Very slowly, stir in half and half, ¼ cup at a time. Then stir in the skim milk, again, very slowly, ¼ cup at a time. Sprinkle in additional ¼ teaspoon of pepper, if desired.

Once milk and half and half have been fully incorporated, slowly stir in noodles and vegetables. Add drained tuna and stir until well combined. Serve.