Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente, about 9 minutes. Drain and set aside.
In a large skillet, heat the olive oil over medium heat. Add the minced garlic and sauté for 1 minute until fragrant.
Add the chopped sun-dried tomatoes to the skillet and cook for 2 minutes, stirring occasionally.
Add the fresh baby spinach to the skillet and cook until wilted, about 2 minutes.
Pour in the heavy cream, then stir in the grated Parmesan cheese, dried Italian seasoning, and crushed red pepper flakes. Cook for 2-3 minutes until the sauce thickens slightly.
Add the cooked pasta to the skillet and toss to combine with the sauce. Season with salt and black pepper to taste.
Allow the pasta to cool completely before transferring it to an airtight freezer-safe container.
Seal the container tightly and label it with the date. Freeze for up to 3 months.
To reheat, thaw the pasta in the refrigerator overnight, then warm it in a skillet over medium heat until heated through, adding a splash of water or cream if needed to loosen the sauce.