Cook ravioli according to package directions. Meanwhile, in a Dutch oven, saute garlic in butter for 1 minute. Add squash and spinach; cook until spinach is wilted, 2-3 minutes longer. Stir in cream, broth and salt. Bring to a gentle boil; cook until slightly thickened, 6-8 minutes.
Drain ravioli; add to squash mixture. Toss to coat. Sprinkle with walnuts.