Cook pasta al dente according to the package. Do not over cook . Drain the pasta and run under cold water to stop cooking it further.
In a large pot bring 1 cup water to a boil. Roughly chop the spinach and add it to the water , pressing gently with the spoon to fit all the spinach in. Cook for 2 minutes until all spinach is wilted. Remove he spinach with a slotted spoon. At this point you can blanch spinach by adding it in a bowl of ice cold water. I did not blanch. Puree the spinach mixture when it cools down and set aside.
For the béchamel/ white sauce in a heavy bottom pan heat up the oil . Add in the flour and cook it for 30 seconds on medium low flame stirring it continuously. Add in the milk with one hand and stir continuously with another to avoid lumps. You can use a balloon whisk to smoothen the lumps . Cook the sauce until it comes to a simmer and thickens. Add in the spinach puree, cook for 1 minute. Add in some salt , pepper and herbs. Switch off the flame.
In another pan, heat up some oil and sautee the garlic , then add in the desired veggies , salt and pepper. Be careful with salt as sauce has it.
Add chilly flakes if desired. Sautee for a minute or so , do not over cook the veggies.
Now time to assemble just before serving. Fold veggies in the sauce . Add in the pasta and give a quick mix. Taste test and adjust seasonings. Serve hot with a teaspoon or two drizzle of extra virgin olive oil . Enjoy as it is or with a side of soup or crusty breads.
Notes
Use desired pasta and veggies. I add warm milk as it expedites the process of simmering.