In a medium-size frying pan, add the oil or water and bring to medium-high heat. Add in onions, celery, carrots, and garlic cloves. Cook until veggies are tender. Turn off heat and set aside.
In a large mixing bowl, combine the lentils or meat with the rest of the base ingredients. Add in the sauteed vegetables and mix together with a large spoon or clean hands.
If making a basic meatloaf, place mixture in a loaf pan, or shallow pan.
If making a singular, seasoned meatloaf, add in those ingredients and mix together well.
For basic mini meatloaves, scoop out about 3/4 cup of mixture and place into a large muffin tin. Using your fingers or back of mixing spoon, press mixture down into muffin tins. Leaving 1/4 space at the top.
For seasoned mini meatloaves, scoop out 3/4 cup of mixture into each muffin cup. Make a well in the center of each one and any extra sauce, or cheese, you would like if desired. Then, using fingers, gather mixture to cover the top.*
Bake meatloaf (meatloaves) for 30 minutes, or until meatloaves are cooked through. (For ground beef, this could take 45 to 50 minutes for the whole meatloaf)
Top with extra cheese or sauces
Let stand for a few minutes before serving
* I like to pulse these in a food processor for a few seconds to make smaller pieces, but not enough that it turns into a flour
*If you want to make each one a different flavor, use a separate bowl and mix seasonings into each mini loaf individually, then place in muffin tins.