Cook fettuccine noodles according to package directions.
In the meantime, dice the onion. Cut the zucchini and summer squash into medallions or half medallions. Cut the bell pepper into thin strips.
Heat a medium frying pan. Cook the ground sausage until cooked through, breaking into smaller chunks as you go. Drain the grease when done, and set aside.
In a separate large pot (preferably heavy-bottomed), melt 2 tbsp butter. Add minced garlic and cook until fragrant, about a minute. Add onion and cook for another 3-5 minutes, stirring occasionally.
Add zucchini, squash and bell pepper. Cook for another 5-6 minutes, stirring occasionally.
Add basil, oregano, garlic powder, salt and the other 2 tbsp butter.
Once the butter has melted, add the flour to your vegetable mix. Stir well to coat everything and let cook for another minute or so. Slowly add milk and whisk to combine. Cook until thickened, another 7-10 minutes.
Add cooked sausage to the sauce and let simmer for a couple of minutes. Toss with the fettuccine and serve.