Heat a large heavy-bottomed pot or Dutch oven over medium heat with the olive oil. Add the diced turkey bacon and cook 5–6 minutes, stirring occasionally, until crisp and browned at the edges. Lift it out with a slotted spoon onto a paper-towel-lined plate. Turkey bacon renders very little fat, so the oil you started with is most of what is left in the pot — leave it there and add the butter.
Add the diced onion and cook 3–4 minutes until softened and translucent. Add the minced garlic and cook another 30 seconds until fragrant, without letting it brown. Sprinkle in the garlic powder, onion powder, dried dill and dried chives and stir constantly for about 30 seconds to bloom the spices.
Pour in 4 cups of the chicken broth, add the bay leaf and season with salt and pepper. Bring to a gentle simmer, then lower the heat. Add the shredded chicken and let it warm through for 2–3 minutes.
Take the pot off the heat and add the softened cream cheese in small chunks, whisking it into the hot broth until fully incorporated. Return to low heat and stir in the cheddar a small handful at a time, stirring constantly — too fast or too hot and the cheese will seize and go grainy.
Add the baby spinach in handfuls, stirring until wilted. Stir in the heavy cream and taste for seasoning. Add the remaining broth if you want it thinner. Remove the bay leaf, stir most of the crisped turkey bacon back in, and simmer 2–3 minutes to bring it together. Garnish with the reserved bacon and sliced scallions.