Form 4 patties out of the turkey sausage. Cook over medium heat until cooked thoroughly cooked through flipping halfway through. Once cooked, add a slice of cheese on each patty to melt. Once slightly melted, remove from heat. Set aside.
In a separate pan, heat 1 Tbsp Olive oil. Add in minced garlic and sauté about 30 seconds. Add in spinach and cook about 5 minutes over low heat until wilted. Stir frequently. Once cooked set aside.
Assemble sandwiches by topping bottom toasted bagel with 2 - 3 Tbsp of cooked spinach, cooked turkey sausage and melted cheese. Top with other half of the bagel and enjoy!
To make-ahead, cook sausage and spinach. Reheat sausage, cheese, and spinach while toasting bagel. Assemble and enjoy.