1. Preheat oven to 350°F.
2. Add oil, chopped garlic and five-spice powder to a small saucepan over medium heat. Cook for 1 to 2 minutes, stirring often, until garlic becomes golden and fragrant.
3. Add flour and cook for 2 more minutes, mashing mixture with the back of a spoon until a thick paste forms. Reduce heat to low and whisk in milk, bringing mixture to a slow simmer.
4. Cook for 2 to 3 minutes, until sauce thickens. Stir in corn, spinach and scallions and cook for about 1 minute more, until spinach wilts.
5. Stir in 1 egg white and baking soda. Transfer mixture to an 8 x 8-inch baking dish and place in preheated oven.