Slice the eggplant and sprinkle with the salt. Let sit for 20 minutes, and then rinse and pat dry.
Sprinkle over the olive oil and the oregano. Place the slices on a cookie sheet and bake for 15 to 20 minutes.
Remove from the oven and spread the marinara sauce over each slice and sprinkle each with a good amount of cheese. Bake until the cheese melts and serve at once.