For the filling:
1. Grill chicken breast until cooked through. Remove to a cutting board and dice into cubes. Transfer the cut chicken into a medium bowl.
2. In medium pan, over medium-high heat, sauté mushrooms in a little olive oil.
3. Add the sun-dried tomatoes ans spinach. Cook for another minute.
4. Add mushroom mixture to bowl with chicken and mix well.
5. Add warm béchamel sauce a little at a time, along with the Parmesan cheese, to the bowl, and mix well.
6. Let it rest until it's at room temperature. (If you want to make the filling ahead of time you can refrigerate it and add it to the pasta later.)
For the pasta:
In a large pot, bring salted water to a boil. Prepare a medium bowl with cold water and ice and set aside.
Cook the pasta until al dente. Remove the pasta from the hot water and shock in it ice water to stop the cooking.
For the assembly:
1. Preheat oven to 475°F.
2. Take a piece of plastic wrap and coat with a thin layer of extra-virgin olive oil. Lay the pasta on wrap then brush olive oil again on top.
3. Add the filling to center of the pasta sheet and fold pasta over it like an envelope.
4. Flip and place in oven safe pan. Pour the vodka sauce into the pan all around the pasta packet. Place the pan in the oven and bake for 10 minutes.
Cut the imbustata into four pieces. Place a piece onto each of four plates. Then spoon the sauce from pan all over imbustata.
Garnish with grated Parmesan cheese, toasted almonds and microgreens.