Optional: olive or pumpkin or squash seed oil for finishing. If you have the time, you can roast the squash seeds with a bit of salt, chop them and sprinkle them on the top of each serving.
Peel, seed and chop the squash into 1/2-inch cubes and place in a medium pot. Add 1/2 cup of water or stock and a pinch of salt. Cover and simmer over low heat for about 15 minutes, stirring oc-casionally. When the squash is soft, purée it with the cooking liq-uid until smooth. Pour the purée into a fine sieve or cheesecloth-lined colander suspended over a bowl to drain off the liquid and thicken the purée. This step is important to the taste and texture of the final dish.
Alternatively, you can bake the squash, cut side down in a 375 F oven for 20-25 minutes. Purée and drain the squash as above.
Heat the remaining stock and keep it simmering close to the pan where you're preparing the oats.
Heat the oil and butter in a saucepan over medium heat, add the minced leeks and sauté until transparent. Add the drained whole oat kernels and sauté until the oats are completely dry.
Turn the heat down to medium-low. Add the wine and stir un-til it's completely absorbed followed by about 1/2 cup of the simmering stock. Continue to add the stock, always 1/2 cup at a time, stirring while the stock is absorbed. The oats will still have a bit of bounce to them even after they're completely cooked. After you have about 2 cups of stock left, taste the oats to see if they're done. If they need more cooking, but you've run out of stock, use some of the simmering water.
Once the oats are cooked to your liking, stir in the squash purée, which will have reduced to 1 cup after draining, and the chopped sage and heat through. Turn off the heat, add the parmesan, stir well and adjust the seasoning.
Now prepare the crispy sage leaves. Heat 2 tablespoons of oil in a shallow frying pan over medium heat. Don't let the oil smoke. If it's too hot the leaves will turn brown and become bitter. Add the whole sage leaves, two or three at a time until crisp but still green. Use tongs to remove them from the oil. Drain on paper towels and sprinkle with a bit of salt.
Divide the oats among four heated plates. Garnish with the whole sage leaves, a drizzle of oil or the toasted pumpkin seeds if you made them.