Line a sheet-pan with parchment paper and drizzle some olive oil.
Add the ground chicken to a bowl with the spinach, breadcrumbs, egg, mustard, diced shallot and spices. Mix well with your hands until evenly incorporated.
With oiled hands, shape the mix into 6 equal burgers. Place the burgers onto the pan, then drizzle each one with more olive oil.
Bake the burgers for about 18 minutes, flipping halfway through. Set them under the broiler for 2 minutes at the end to brown.
Serve with a salad or in a bun with your favorite toppings.