In a large sauté pan over medium-high heat, sauté pancetta or bacon until crispy, then remove to drain. Remove all but 1 tbsp of bacon fat from pan.
In same pan, sauté onion for 4 minutes to soften (not brown), then add squash.
Add garlic, sage, wine, vinegar and water and cook for about 6 minutes, until squash is tender. Taste and season.
Spoon warm squash over spinach greens, on a plate or platter and dollop ricotta on top.
Drizzle with olive oil and finish with a little sprinkling of salt & pepper. Serve immediately.