Cook pasta according to the package directions, omitting salt and fat; drain well.
While pasta cooks, place tomatoes on a jelly-roll pan lined with foil. Broil 8 minutes or until the tomatoes are beginning to blacken.
While the tomatoes cook, heat a large saucepan over medium-high heat. Add the canola oil to the pan; swirl to coat. Add diced shallots, minced garlic, and thyme; saute 2 minutes or until tender, stirring frequently.
Add the tomato paste; cook for 2 minutes, stirring occasionally. Add the flour; cook 1 minute, stirring constantly. Stir in the milk, black pepper, and salt; bring to a boil. Cook 4 minutes or until thick and bubbly, stirring frequently. Remove from the heat.
Add the spinach, stirring constantly until the spinach starts to wilt. Add the shredded cheddar cheese, and stir until smooth. Stir in the cooked pasta. Top with the roasted tomatoes.