Heat oven to 450°F or 425°F convection with the rack in the upper middle.
As the oven heats up, combine the shallots, vinegar, extra virgin olive oil, coconut aminos, fish sauce, and Magic Mushroom Powder (or salt) in a large bowl. Stir well and then add the chicken to the marinade.
Shake off the excess marinade and transfer the chicken to a rimmed baking sheet. (Leave the marinade in the bowl, because you’re going to dump the mushrooms in next!)
If you have a combination of different mushrooms, add the sturdier mushrooms (e.g. sliced King Trumpet, button, shiitake, etc.) to the marinade first. Toss well and then transfer them to the rimmed sheet in a single layer.
Using delicate mushrooms (e.g. enoki or brown clamshell mushrooms)? Toss them carefully in the marinade after you’ve removed the sturdier ones so they don’t break apart.
Arrange the chicken, mushrooms, and shallots in a single layer on the sheet pan.
Pop the sheet pan dinner in the oven and roast for 25 to 35 minutes, rotating the tray 180° at the halfway point.
The dish should be done when the chicken is cooked through (a meat thermometer should read 165°F in the thickest part of the thigh or 150°F if you’re using chicken breasts) and the liquid from the mushrooms has mostly cooked off.
Sprinkle on fresh herbs and serve immediately with a simple vegetable side dish!