Preheat oven to 400°F for toasting the buns.
Dump the ground chicken into a large sauté pan over medium-high heat and crumble it as it cooks.
Add the diced onions to the pan with the ground chicken, stirring well.
Once the ground chicken is fully cooked, mix in the marinara sauce, basil pesto, salt, and pepper.
Reduce heat to low, stir in the shredded Parmesan cheese, and continue cooking.
Spread garlic margarine on brioche buns and lay them on a baking sheet.
Toast the buns in the preheated oven for 5 minutes.
Assemble the burgers by spooning the chicken mixture onto the bottom buns, topping with mozzarella, and covering with the top buns.