Heat olive oil in a large sauté pan or skillet. Add onion, pepper, cauliflower and garlic and sauté 8 minutes. Stir in oregano, smoked paprika and marinara sauce and heat until bubbly.
Preheat oven to 350 F.
In a large 9 × 13 inch baking dish, arrange 3 sheets of lasagna noodles, 3 ounces of spinach, ½ of the vegetable-marinara mixture, ¼ cup sour cream (dollops), and 1/3 cup plant-based cheese. Repeat layers.
Layer the lasagna noodles, spinach, vegetable mixture, plant-based sour cream, and plant-based cheese.
Cover with foil and bake for 45 minutes. Remove foil and bake for an additional 15 minutes, until browned and cooked through.