Preheat oven to 375 degrees F. Spray a large rectangular baking dish with nonstick cooking spray.
In a large (12-inch) skillet, heat olive oil over medium heat.
Add diced onion and cook until beginning to soften; 3 minutes. Stir in garlic and cook for 30 seconds, then crumble in ground turkey. Cook until no longer pink; about 6-8 minutes.
Stir in taco seasoning and tomato paste and cook for about 1 minute. Stir in chicken broth and black beans. Simmer, stirring occasionally, until sauce is thickened; about 7-10 minutes. Season with salt and pepper if desired.
Arrange taco shells in a large rectangular baking dish (you may need more than one baking dish, depending on the size). Using a slotted spoon, scoop about 2-3 tablespoons of the meat mixture into each taco shell. Top with 1-2 tablespoons of the shredded cheddar cheese.
Bake in the preheated oven for 12 minutes, or until cheese is melted and taco shells are crispy and just beginning to brown.
Top with your favorite toppings, like lettuce, tomatoes and sour cream. Serve immediately.
Leftover can be store in the refrigerator in a tightly sealed container for up to 2 days.