Make slits around the spaghetti squash as if you were going to cut it in half length ways. About 5 slits on one side and 5 slits on the other side. Then make two additional slits in the center of each half.
Place whole spaghetti squash in microwave and microwave at 70% power for 10-15 minutes or until soft. (Rotate the side it sits on every five minutes.)
While spaghetti squash is cooking, add oil to a very large skillet and cook ground chicken or turkey on medium, about 8-10 minutes. Remove from heat.
Preheat oven to broil and line a baking sheet with foil.
When spaghetti squash is done cooking, use a dish towel to remove it from the microwave, it will be very hot. Carefully cut it in half and remove seeds. I found that when cooking the spaghetti squash whole, the seeds are harder to remove but not impossible. I ended up using kitchen shears to cut them out and then using a fork to kind of sift the stragglers out.
Leaving about an ½ inch around the shell, remove spaghetti squash strands from shell. If you plan to make boats, you will want to keep the boats intact, if not then it doesn’t matter. Add the spaghetti squash to the skillet and mix with chicken and sauce.
Divide the mixture back among the two half shells, top with mozzarella cheese and pepperoni. (If you don’t want to mess with the shells you can just top the mixture with cheese and pepperoni and put that in the oven, as long as you used an oven safe skillet.) Broil for 3-5 minutes or until golden brown and bubbly. WATCH IT, this happens fast! Garnish with parsley, basil, and red pepper flakes if desired.