For the breadcrumbs: The night before, toast the wheat bread and leave out overnight to dry out.
The following day, crumble the toasted wheat bread to the consistency of pebbles and sand in a small bowl and set aside.
For the potato base: Preheat the oven to 350 degrees F.
Dunk each piece of potato in the butter and pat dry a little. Line the bottoms and all the way up the sides of 6 cups of a 12-cup muffin tin with 2 to 3 layers of potato slices (about 15 slices per muffin cup), so that the potatoes come up about 1/4 inch over the top. Fill the empty cups with water. Bake until the potatoes are golden, about 25 minutes. Set aside.
For the chicken meatloaf: Raise the oven temperature to 375 degrees F.
In a large bowl, add the lemonade and reserved breadcrumbs and stir until mushy. Add the Parmesan, onion, Worcestershire, salt, chile flakes, garlic, egg and a few grinds of black pepper. Stir until it forms a loose paste. Add the chicken and tomatoes and fold with your hands until everything is combined. This should be sticky!
Press some of the chicken mixture into each potato-lined muffin cup. Press a sprig of thyme on top of each. Refill each empty cup with water. Bake until the meatloaf edges are golden brown, about 15 minutes. Allow to cool slightly for 5 minutes, then remove each loaf with a spatula or butter knife. Serve with Meatloaf Gravy if desired.
In a small pot on medium heat, add the butter and flour. Cook, stirring constantly, until the mixture stops foaming and deepens a bit to a light golden color. Add the Worcestershire and garlic and whisk to combine. Add the thyme, then whisk while slowly pouring in the stock and lemonade. Whisk until reduced and thickened to gravy consistency, about 5 minutes. Remove and discard the thyme. Season with salt and pepper.
I'm aware that meatloaf seems best with gravy, but this is such a juicy meatloaf that I didn't feel the need for it. But I know there's just a crew of #teamgravy out there and I aim to please, so this gravy accompanies this meatloaf recipe quite well. Enjoy it wit or wit-out!