Preheat oven to 350 degrees. Spray a 9 x 9 inch baking dish with PAM. In a saucepan heat 1 tablespoon of olive oil over medium heat. Add bell pepper, onion, chile peppers, tomatillo, zucchini and oregano. Cook until tender, about 5 minutes. Add garlic and cook until fragrant. Stir in salt, pepper and cayenne.
In a small bowl, combine flour and water and whisk to blend. Add to vegetable mixture. Add milk and stir until well blended. Reduce heat and simmer until slightly thickened, about 3 minutes. Add 1/2 cup of the Monterey Jack cheese and stir until melted. Remove from heat and stir in sour cream.
In a skillet, heat remaining 1 tablespoon olive oil over medium heat. Add shrimp. Stir until shrimp just turn pink, about 2 minutes. Stir in half of the vegetable cream sauce mixture and half of the tomatoes. Remove from heat. Lay out flour tortillas and fill each equally with the shrimp mixture. Roll tightly and place seam side down in the baking dish.
Top burritos with remaining half of the vegetable cream sauce mixture. Cover the pan with foil and bake 30 minutes or until thoroughly heated. Top with remaining 1/2 cup of Monterey Jack cheese, sliced green onions and remaining chopped tomatoes. Serve immediately.