Bring a large pot of salted water to a boil, then cook the spaghetti until al dente (check 1–2 minutes before package time). Meanwhile, reserve about 1 cup pasta water, then drain.

Heat olive oil in a large skillet over medium heat, and add minced garlic and red pepper flakes; sauté until fragrant and just turning golden, about 30–45 seconds.

Stir in the sliced sun-dried tomatoes; cook for another minute so they release flavor and sizzle slightly.

Pour in the heavy cream and bring to a gentle simmer, stirring so it doesn’t scorch at the edges; add Italian seasoning, salt, and pepper to taste.

Stir in the grated Parmesan until the sauce becomes smooth and slightly thickened; look for a glossy finish and no grainy cheese bits.

Fold in the fresh spinach in batches, and stir until wilted and bright green; then toss the cooked spaghetti into the skillet, adding reserved pasta water a splash at a time to loosen the sauce to your preferred silkiness.

Serve warm and enjoy the steam and aroma.