Start by bringing a large pot of water to a boil. Add a pinch of sea salt to enhance flavor. Once bubbling, toss in the penne pasta. Cook according to the package instructions, usually around 11-13 minutes for that perfect al dente texture. Trust your taste buds here; occasionally sample the pasta to check.

In a large skillet, heat 1 tablespoon of olive oil over medium heat. Once hot, add the diced onion. Sauté until they turn soft and translucent, about 3-4 minutes. Follow up with minced garlic and cook for another minute until fragrant. This duo creates a solid base for the marinated pasta.

Now, let's introduce the mushrooms into the skillet. Cook for about 5-6 minutes, stirring occasionally. You want them to soften and release their flavor. That earthy taste will elevate your marinara experience.

Next, pour in the marinara sauce and mix well. Adjust the heat to low and let it simmer for about 5 minutes. This allows the ingredients to meld nicely. Use this time to add onion powder, Italian seasoning, and crushed red pepper flakes, if you’re feeling adventurous.

If you chose to incorporate cream, this is where it comes in. Pour ½ cup of heavy cream into the sauce. Stir thoroughly and watch as the sauce becomes a luscious blend. Then, mix in the grated Parmesan cheese for an irresistible cheesy kick.

By now, the pasta should be ready. Drain it, but don’t rinse—it’s like a golden rule for pasta! Toss it directly into the skillet with marinara. Give it a good mix, so every piece of penne is lusciously coated in that beautiful sauce. Stir in your fresh basil leaves at this stage.

Taste the pasta. Does it need a sprinkle of salt or perhaps more cheese? Adjust to your liking. I'm a firm believer in tasting food at every stage—it’s like a love letter to your taste buds!

Once satisfied, serve the penne pasta on warmed plates. Garnish with more fresh basil or a sprinkle of grated Parmesan if desired. Now, take a moment to appreciate the beauty of your creation. You're done!