Preheat oven to 400 F. Pierce each potato with a fork 1-2 times each. Place on baking tray and bake for 50 min to 1 hour until soft in the middle and crispy on the outside.
For the filling:
In a large frying pan over medium heat, cook the ground meat and onion until completely browned and the beef is broken into small pieces, and drain the excess grease (in tin foil or an old tin can, just not down the drain).
Add flour and stir well until there is no white left.
Add in the Worcestershire sauce, tomato paste, beef bouillon, garlic & onion powder, thyme, and salt & pepper. Mix well.
Add the beef broth slowly, stirring constantly.
Add in the mixed vegetables and turn heat to low/medium heat and let simmer for 10-15 minutes or until vegetables are soft and mixture has thickened, stirring occasionally. Remove from heat when ready to serve.
To assemble:
Slice each baked potato lengthwise down the middle and squeeze the ends to poof out the potatoes a bit.Spread a pat of butter inside each potato and spoon the shepherd's pie filling into the middles. Serve warm!
Notes
Refrigerate: up to 4 days. Freeze: up to 3 months. Freeze together assembled or filling and potatoes separately.Thaw overnight and bake at 350 ℉ for 45-50 minutes until warmed through, or for 1.5 hours if baking from frozen.