Remove the backbone from the chicken using kitchen shears and lay it flat, skin side up on a sheet tray lined with parchment paper and bake in the oven for 60 to 70 minutes or until golden brown and cooked through.
In a medium bowl whisk together the butter, pumpkin, maple, sage and salt and pepper until combined. Keep cool.
Cabbage: In a large sauté pan over medium high heat add in the butterand cook the onions for 10 to 15 minutes or until browned and tender.
Next, add in the cabbage and sauté for 10 to 15 minutes over medium heat. Stir in the vinegar, brown sugar, salt and pepper and braise for 10 minutes.
Serve the cabbage alongside the roasted chicken with the pumpkin butter.