Method

• 01
  With a large, sharp knife, carefully split the squash in half lengthwise and remove seeds and membranes with a spoon. Brush the flesh of each squash half evenly with 1/2 teaspoon olive oil, then sprinkle each half with 1/4 teaspoon salt and 1/16 teaspoon of black pepper.
• 02
  Place squash, skin side up, in a 9x13 baking dish. Microwave on full power for 15-20 minutes, until the tops give slightly under pressure when gently pressed (checking for doneness every couple of minutes at the end of cooking time.)
• 03
  Let sit about 10 minutes until cool enough to handle (or handle with oven mitts), and then use a fork to shred the squash into a large serving bowl. (If your squash is a bit overcooked and a little watery, you can place it in a colander for a few minutes to drain before using a slotted spoon to transfer it to the bowl.
• 04
  Meanwhile, while the squash is cooking, toast walnuts in a small skillet over medium-low heat, stirring frequently to prevent burning. Remove from heat as soon as the walnuts smell fragrant or begin to lightly brown. Set walnuts aside and carefully wipe out skillet.
• 05
  In the same skillet, over medium-low heat, melt butter and cook, gently swirling the pan or stirring occasionally, until the butter has foamed and begun to turn a light golden brown. (This will take about 3-4 minutes, varying greatly depending on how powerful your burners are.)
• 06
  Add the sage and continue browning the butter a little further, about 1 minute, just until the butter has turned a richer golden-brown with little specks of milk solids in the bottom of the pan. Remove the butter from the heat and stir in the remaining 3/4 teaspoon salt and 1/3 teaspoon black pepper.
• 07
  Add toasted walnuts and browned butter sauce to spaghetti squash and stir gently to thoroughly combine. Serve immediately from the bowl, or (if you'd like to present this as a stuffed spaghetti squash), by piling the squash mixture back into one of the spaghetti squash "shells."