Start by cutting the top off the squash and removing the seeds (just like when you make a jack-o'-lantern).
Coat with cooking spray. Place on a baking sheet with the tops and roast for 45 minutes
Add the butter and brown sugar directly into the shell.
Using a fork, gently remove the flesh from the sides and bottom of the shell. Leaving a border of unmashed flesh to keep the shell stable and to prevent collapsing (about a half-inch will do).
Salt & pepper to taste and serve.
Notes
This recipe calls for eight squash, but only serves four shells as it takes two squash to fill one shell (as pictured). Just remove the flesh from the extra squash, and add it to the one you're serving before mashing. For this recipe, I used dumpling squash, but you can use any pumpkin or similarly shaped squash that you like to cook with such as Kabocha, Buttercup, or Acorn squash (you may have to trim the bottom to have it stand upright).As you’ll need to make extra to fill the shells, butternut squash is a great addition to whatever squash you’re filling.You can use lids to keep the squash warm for up to 15 minutes. Anything longer will require keeping them in a warm oven.Depending on the size of your squash, cooking times will vary. Check for doneness at around 40 minutes. It's done cooking when the flesh is tender all the way through to the skin.