Preheat oven to 400°F.
In a large bowl, mix turkey, parmesan, panko, shallot, egg, garlic, lemon zest (ZEST ONLY! NOT THE JUICE!), 1 tbsp thyme leaves, salt, and red pepper flakes with your hands until just combined. Don’t over-mix or they’ll be tough!
Gently roll turkey mixture into 8 meatballs.
Warm oil in a large ovenproof skillet over medium-high heat. Sear meatballs in two batches until golden brown on three sides, about 2 minutes per side. Remove meatballs from skillet.
Melt butter and add mushrooms and remaining thyme. Cook until beginning to brown, about 2 minutes. Season with salt.
Place turkey meatballs over/around the mushrooms. Squeeze 1/2 of the lemon over top and cut the other half into wedges. Place skillet in oven for 8 to 10 minutes, or until internal meatball temperature is 150°F.
Serve with arugula, more parm, and lemon wedges.
