Bring a pot of water to a boil and cook gnocchi according to directions on the package.
Place butter in a shallow skillet over medium heat. Immediately begin whisking it. It’ll start to foam and within 2-3 minutes, brown bits will start showing up at the bottom. At this point in time, I usually will take the skillet off the heat and start swirling the butter around in the pan in the air so it doesn’t quickly go from brown to burned. Once you see a nice brown color in the butter (and start smelling the amazingness), you’ve achieved brown butter.
Carefully add the sage leaves to the brown butter and put over medium heat again. At this point, the butter shouldn't burn but just cook the leaves enough so they're slightly crisp and immediately remove butter and sage leaves from stove. Drain sage leaves on a paper towel and set aside.
Whisk pumpkin puree into the butter then place skillet over medium heat again and add spinach. Cook until spinach has wilted.
Drain the cooked gnocchi and add to the skillet. Toss until all is coated in the sauce and season with salt and pepper, to taste.