(Gluten Free) (Vegetarian) Smoky Eggplant Pizza

White sauce:
2 tablespoons of butter
2 tablespoons gluten-free flour
1 teaspoon garlic, minced
One cup of milk
1/4 teaspoon salt
1/4 teaspoon pepper
1/4 cup Parmesan cheese

Smoky eggplant:
1 1/2 cups eggplant
1/2 teaspoon smoked paprika
1/2 teaspoon ground fennel seed
1/2 teaspoon dried oregano
1/2 teaspoon salt
Pinch of pepper

Pizza:
1/4 cup shredded onion
11/2 cups, Italian cheese blend
Gluten-free pizza crust