Heat 2 tablespoons olive oil in a large skillet over medium heat. Once hot, add onions and ¼ teaspoon salt and saute until onions are translucent, about 5 minutes. Stir in the garlic and cook for 3 minutes. Add the eggplant and 1 tablespoon olive oil and cook, stirring occasionally, for 8 minutes or until the eggplant has softened. Stir in the zucchini, tomatoes, cumin, and paprika and cook over medium heat, stirring occasionally, for 5 to 7 minutes or until all the vegetables are tender. Season with salt and pepper. Remove mixture from heat and let cool to room temperature.
Divide the ratatouille mixture in two and pile it by the heaping spoonful into the baguettes. Garnish each one with goat cheese and press down on the top of the baguette to combine.
Wrap sandwiches tightly with plastic film or wax paper or serve immediately.