Bring a large pot of salted water to a boil and cook the ravioli according to package instructions (fresh 3–4 minutes, frozen 4–6 minutes). Drain and set aside, reserving a splash of pasta water.
Meanwhile, heat a 12" skillet over medium heat and melt the butter.
Add the minced garlic and cook 1 minute until fragrant, stirring so it doesn't brown.
Add the chopped sun-dried tomatoes and cook 1–2 minutes, stirring occasionally.
Add the chopped baby spinach and cook 1–2 minutes until wilted.
Pour in the heavy cream and bring to a gentle simmer; cook 4–5 minutes until slightly thickened, stirring occasionally.
Reduce heat to low and gradually stir in the grated Parmesan until melted and the sauce is smooth.
Season the sauce with salt, black pepper, and nutmeg to taste.
Add the cooked ravioli to the skillet and gently toss to coat, thinning the sauce with a splash of reserved pasta water if needed.
Remove from heat, stir in the chopped fresh basil, and serve immediately.