Slice the acorn squash in half and scoop out the seeds. Place the two halves face-down on a baking dish and place in the oven to bake for 40 minutes.
When the squash has about 25 minutes left to bake, heat a skillet over medium heat.
Add in the sausage and onion to cook, stirring occasionally until the sausage is browned and the onions cook down.
When the squash has about 5 minutes left to cook, add in the pear and sage to the skillet. Season with salt and pepper to taste. Stir everything together and allow to cook until the squash is ready.
Remove the squash from the oven transfer to a plate. Fill the squash full with the sausage and pear mixture and serve.