Skinnytaste Eggplant Rollatini with Spinach

2 medium Italian eggplants, cut lengthwise into 10 (1/4” thick) slicesKosher salt, black pepper1 ½ c. homemade or store bought marinara sauce1 egg½ c. part skim ricotta cheese½ c. grated Pecorino Romano cheese, plus more for serving8 oz. frozen spinach,…