Saute onions in a bit of oil until beginning to soften. Add ground beef and cook through, draining grease if necessary. Stir in taco seasoning and tomatoes and keep warm.
In a separate small pot, warm refried beans on low.
Carefully mold your tortillas to the oven proof molds and place in the oven for 2-3 minutes. Pay close attention as the tortillas can burn easily. Take out when lightly browned and set aside still in molds.
Set out all toppings and fillings so everyone can layer their bowl their own way.
Notes
Leftover meat and beans may be stored in the fridge for up to 3 days.
Any oven-proof bowl turned upside down will also work as a mold.
If you have very small tortillas you can use a muffin tin. Try it both right side up with tortillas in the cups, or upside down between the cups to see what works for your tortillas.
Nutrition facts are for tortillas with beef and beans. Toppings are additional.