Preheat your oven to 350° F. Line a rimmed sheet pan with foil.
In a large bowl, whisk together the egg, salt, pepper, garlic powder, onion powder, and thyme.
Add the ground beef, almond flour, and Parmesan. Gently mix, just until uniform.
Shape the mixture into a rectangular loaf (as shown in the video) and place it on the prepared baking sheet. Brush the loaf with ketchup.
Bake the meatloaf until the center of the loaf registers 160° F, 50-60 minutes.
Rest the meat for 15 minutes before slicing and serving.
One of the most important things you can do to keep your meatloaf tender and fluffy (not a brick!) is to handle it lightly. Mix just until everything is incorporated, and when you shape it into a loaf, be gentle.
It's always best to bake a meatloaf on a large rimmed baking sheet so that the outside can crisp up. If you bake it in a loaf pan, it will bake inside its own juices and won't crisp up.
A metal pan is better. I tried making this recipe with foil and with parchment paper. The meatloaf turns out much better when the pan is lined with foil, probably due to better heat distribution.