Pre-heat the oven to 350 degree Fahrenheit (180 degree Celsius).
Cook pasta al dente according to the package directions.
While pasta is cooking, melt one tablespoon butter in a medium sized skillet over medium heat and add mushrooms. Stir fry till golden brown. Add the baby corn and bell pepper fry for a couple of minutes. Transfer to a baking dish and sprinkle salt, pepper, dried oregano and dried basil. Mix well.
To prepare the sauce, to the same skillet on medium heat, add another tablespoon butter and minced garlic. Add chopped spinach and saute till dry.
Reduce the heat to low. Add all-purpose flour and fry for a couple of minutes.
Add milk, whisking constantly to avoid lumps. Stir continuously till the sauce starts to thicken. Mix in the pepper jack cheese and cook for a minute or two till the cheese melts. Season with salt and pepper. Remove from heat. Spinach Alfredo sauce is ready.
Once the pasta is cooked, drain the pasta and add it to the sauteed vegetables in the baking dish. Mix well. Season with salt and pepper.
Pour the spinach Alfredo sauce over the pasta. Garnish with sliced tomatoes.
Bake at 350 degree Fahrenheit (180 degree Celsius) for about 15 minutes.
Seve hot.