Preheat oven to 350F.
Grease a 9 by 3 in cake or square pan.
Cook pasta in a large pot of boiling water for 6-7 min, just shy of al dente (pasta will continue cooking in the oven). Drain and set aside to cool (at least 5 minutes).
In a bowl, whisk the eggs, ricotta, and parmesan cheese together. Add spaghetti and toss to blend.
Transfer the spaghetti to prepared baking pans, pressing it down to form a crust.
In a large skillet over medium heat, brown meat. Transfer to a bowl. To the same pan, cook the vegetables until softened. Add the beef back in along with oregano and tomato sauce. Cook for about 5 minutes until well combined and the sauce thickens
Spoon the beef veggie sauce mixture over the spaghetti. Sprinkle with mozzarella cheese, if desired (see note)
Bake for 25-30 minutes. Cool for at least 20 minutes before cutting.
To serve:for baby, cut pie into little pieces. The sauce will separate so just pour on top of pasta.