Cut the squash in half lengthwise to make two equal sides
Place the squash cut side down and bake until the squash is tender when pressed with a finger
Remove from the oven and allow to cool for 10 minutes
Meanwhile, in a large frying pan brown the sausage over medium heat until cooked through
Remove the meat but leave the remaining fat and add the onion and garlic with a big pinch of salt then reduce the heat to low and allow to sweat until soft
Add the apples and cook until soft but not falling apart
Then add the meat and buckwheat back to the frying pan, toss to combine, and then remove from the heat
Flip the squash over and discard the seeds then scoop the pulp away from the skin leaving an inch of flesh around the skin to hold the squash shape
Mix the squash flesh with the sausage and buckwheat filling then return to the squash body
Top with the grated cheddar and return to the oven until the filling is warm and the cheese is melted, about 15 minutes