In a bowl, mix the eggs, water, 2 cups flour, and salt. Gradually mix in the remaining flour until smooth. Divide dough into 2 parts. Cover, and set aside in the refrigerator 20 minutes.
In a skillet over medium heat, cook the ground chicken until evenly brown; drain.
In a food processor, mix the chicken, spinach, and onion. Transfer to a bowl, and mix with butter, 3 tablespoons Asiago cheese, salt, garlic powder, nutmeg, and pepper.
On a lightly floured surface, roll out each part of the dough to 1/8 inch thickness. Cut into 2 inch squares. Place about 1 teaspoon of the chicken mixture in the center of 1/2 the squares, and top with remaining squares. Seal the edges of the squares with a moistened fork to form the ravioli.
Bring a large pot of lightly salted water to a boil, and cook the ravioli in small batches for about 8 minutes, or until al dente. Drain, and rinse under cold water.
Place the marinara sauce in a saucepan, and cook until heated through. Serve ravioli topped with marinara sauce and remaining Asiago cheese.
