Drain tofu by placing slices between sheets of paper towels. Place the tofu and paper towels between two dinner plates, and store in the refrigerator 4 hours or overnight, changing paper towels as they soak through.
Prepare the spaghetti squash. Cut the squash in half and clean, removing seeds. Poke holes in the flesh with a fork. Add olive oil, garlic, salt, and pepper to cavity. Bake for 40 minutes in an oven preheated to 350. Remove the squash from the oven and place somewhere cold for 20 minutes before drawing a fork across the squash flesh to create "spaghetti."
Spray a large sautee pan with nonstick cooking spray. Cut the tofu into cubes, and cook on medium heat for 20 minutes, until crisp on the outside and firm to the touch.
Add mushrooms and artichoke hearts to sautee pan, and cook for 5 minutes.
Add spaghetti squash to pan, heat until warm.
Combine the pesto and cream in a small bowl. Stir into sautee pan.