Boil, drain, and mash the sweet potato. Set it aside to cool.
Remove the naan dough from the fridge and let it come to room temperature, or use freshly made dough.
Preheat the oven to 400°F.
On parchment paper, roll out dough to about 1/4 inch thick and cut it to fit into the bottom of your greased pan.
Poke holes in the dough with a fork and bake for 8-10 minutes.
Chop the onion and soften it in a pan with a little butter or oil on medium heat.
Add the beef to the pan and cook until lightly browned.
Crumble the beef bouillon cube into the pan and add the water, thyme and peas, and cook for 8-10 minutes
Make a paste with the cornstarch and 1 tablespoon of cold water. Add it to the pan and cook for 2 to 3 minutes, stirring continually, until thickened. Set aside to cool
Grease the pan and place the dough in the bottom of each cavity.
Fill the cavities with about 2 tablespoons of the beef mixture and evenly divide and spread the mashed sweet potato over the top.
Rough up the sweet potato surface with a fork and sprinkle grated cheese on top.
Bake at 400°F for about 20 minutes until golden on top.
Serve while warm, or refrigerate and reheat before serving.