Finely dice the carrots, celery, and onion. You want small, uniform pieces (about 1/4 inch) so they melt into the sauce as it simmers. This is your soffritto -- the aromatic base of every great Bolognese.
Heat 2 tablespoons of olive oil in a large, heavy-bottomed pot or Dutch oven over medium heat. Add the diced carrots, celery, and onion. Cook, stirring occasionally, for 6-8 minutes until the vegetables are soft and the onion is translucent. You want them tender, not browned.
Add the minced garlic and cook for 30 seconds, stirring constantly, until fragrant. Do not let it brown.
Push the soffritto to the edges of the pot and increase heat to medium-high. Add the ground turkey to the center. Break it up with a wooden spoon or spatula into small crumbles. Cook for 5-6 minutes, breaking it up as it cooks, until no pink remains and you start getting some golden-brown bits on the meat. Those browned bits are flavor.
Stir the soffritto back into the turkey so everything is combined.
Add the tomato paste and stir it into the meat mixture. Cook for 1 minute -- this concentrates the tomato flavor and removes the raw paste taste.
Pour in the red wine. Scrape up any browned bits from the bottom of the pot with your spoon. Let the wine simmer for 1-2 minutes until mostly evaporated. You will smell the alcohol cook off.
Add the entire can of San Marzano crushed tomatoes. Stir in the Italian seasoning, salt, black pepper, and red pepper flakes (if using).
Bring the sauce to a gentle simmer. Reduce heat to low, partially cover the pot (lid slightly ajar), and let it simmer for 20-25 minutes, stirring occasionally. The sauce should thicken and the flavors should deepen. Taste and adjust salt as needed.
About 10 minutes before the sauce is done, bring a large pot of generously salted water to a boil. Cook the penne according to package directions (usually 10-12 minutes) until al dente. Reserve 1/2 cup of pasta water before draining.
Drain the pasta and toss it directly into the sauce. Stir to coat, adding a splash of reserved pasta water if the sauce seems too thick. The starchy water helps the sauce cling to the pasta.
Divide among 4 bowls. Top each serving with 1 oz of freshly grated Parmesan and a few torn basil leaves. Serve immediately.
Meal Prep Strategy: Make the sauce in a double batch (4 lbs turkey) and freeze in individual 1.25-cup portions in freezer bags or deli containers. Lay bags flat to freeze for easy stacking. On meal prep day, just thaw a portion in the fridge overnight, boil pasta, and top with Parmesan. Total active time on a weeknight: 12 minutes.