Place the block of feta in the middle of a large baking dish and surround it with the cubed pumpkin and garlic cloves.
Add the sage leaves, fresh thyme, and ground nutmeg, drizzle the olive oil over everything, and season liberally with salt and pepper.
Roast in the oven for 30 minutes until the pumpkin is soft.
Meanwhile, heat up a large pot of salted water until boiling, and then cook the pasta for 10 minutes until al dente, or according to the instructions. Reserve 1½ cups of pasta water.
When the pumpkin is soft, remove the baking dish from the oven.
Remove roughly half of the cubed pumpkin and set to one side.
Remove the roasted garlic cloves from their skins.
Mix the garlic in with the feta and the cubed pumpkin.
Use the reserved pasta water to make a smooth sauce.
Add the spinach to the pan.
Add the cooked pasta to the pan.
Stir everything together until the spinach has wilted and the pasta is coated in the pumpkin feta sauce.
Stir in the reserved cubed pumpkin.
Serve topped with toasted pine nuts, as well as crispy sage leaves and further feta if desired.