Step 1: Preheat oven to 375°F (190°C). Lightly brush eggplant slices with olive oil and season with salt and pepper.
Step 2: Arrange eggplant slices on a baking sheet in a single layer. Bake for 10-12 minutes until pliable but not fully cooked. Remove and let cool slightly.
Step 3: In a bowl, mix ricotta, spinach, sun-dried tomatoes, garlic, Parmesan, oregano, salt, and pepper until well combined.
Step 4: Place 1-2 tablespoons of the ricotta mixture at one end of each eggplant slice. Roll up tightly from the short end.
Step 5: Arrange roll-ups seam-side down in a baking dish. Bake for 15-18 minutes until heated through and lightly golden.
Step 6: Serve warm with marinara sauce for dipping.