1. Space the oven racks so that both may be used, and preheat oven to 425 degrees F. Spray a rimmed baking sheet with vegetable cooking spray.
2. Place asparagus, onion, and bell pepper on the baking sheet. Drizzle with oil and sprinkle with salt and pepper; toss to distribute and coat the vegetables evenly. Bake until vegetables are tender and roasted, about 20 to 25 minutes.
3. Gently unroll pie crust if using and place in an ungreased 9-inch deep-dish pie pan. Press against the bottom and sides of pan, molding into the shape of the pan. Use a fork to poke holes in the base and sides. If using the pie shell, also poke holes with a fork in the base and sides. Bake until lightly golden, about 10 to 12 minutes. Cool slightly.
4. Reduce heat to 375 degrees F. Place roasted veggies in the crust. Add ricotta cheese in dollops evenly across the vegetables.
5. In a small bowl, whisk together egg and egg whites. Add milk and thyme and lightly whisk to combine. Pour this mixture over the vegetables. Top with tomato slices.
6. Bake at 375 degrees F until a toothpick comes out clean when poked through the filling, about 40 to 45 minutes. Let rest at least 15 minutes before serving, or cool to room temperature.
7. Serve warm or at room temperature. Garnish with thyme sprigs, if desired.
Source: Hannaford fresh Magazine, March - April 2013