In a large mixing bowl, combine cooked lentils, chopped spinach, breadcrumbs, Parmesan (if using), onion, garlic, cumin, smoked paprika, salt, and pepper. Use a fork to mash the lentils slightly to help bind the mixture. This should take about 5 minutes.

Stir in the large egg until fully incorporated. If the mixture appears too wet, gradually add more breadcrumbs until it holds together well. This should take around 3 minutes.

Divide the mixture into four equal parts and gently shape them into patties about 1-inch thick. This shaping step will take roughly 5 minutes.

In a large skillet, heat about 2 tablespoons of olive oil over medium heat. Allow the oil to shimmer, indicating it’s hot enough to cook the burgers thoroughly. This should take about 2 minutes.

Carefully place the patties in the skillet and sauté for about 4-5 minutes on each side, or until they turn golden brown and are heated through.

Once cooked, remove the burgers from the skillet and allow them to rest for a minute. Serve on buns with your favorite toppings.