Heat olive oil over medium heat in your cast iron skillet (or pan). Sauté the garlic, carrots, and onions until soft and fragrant. Add in the ground beef. Cook until browned and drain.
Season the meat with salt, pepper, thyme, (red pepper flakes if using). Give everything a stir. Then add in the cubed potatoes, tomato paste, stout beer, and beef broth. Give everything a stir again.
In a small dish combine the flour and cold water and whisk until smooth. Slowly add into the meat mixture and stir until incorporated.
Let simmer for a few minutes until slightly thickened.
Top the meat mixture with the pie crust. Slighly press down and into the pan. Pinch the edges with your fingertips.
Make an egg wash by whisking together an egg and some cool water. Then brush the egg wash over the pie crust. Sprinkle with some garlic powder. Use a sharp knife to make a few slits in the pie crust to let vent while it's baking.
Bake for about 30 minutes at 350 degrees F until the pie crust is golden brown. Then let set for a few minutes before slicing and serving.
