3 T butter
3 T flour
2 c. milk
1 c. grated cheese (cheddar or Swiss work well - something with a sharp, strong flavor)
1 10-oz. box frozen spinach, defrosted (leave out overnight or microwave until not frozen)
salt and pepper
1. Preheat oven to 375°F. Spray, grease, or butter the bottom and sides of the soufflé dish so it's ready.
2. Defrost spinach in microwave and squeeze out as much water as possible over the sink.
3. Heat butter in a saucepan over medium heat. When melted, add flour and cook for 2 minutes, stirring with a whisk. (This is to prevent a raw flour taste.)
4. Add milk and increase heat until milk boils. Cook about 5 minutes until thickened (you want slightly thicker than a syrup-like consistency). Once thickened, remove from heat. (This is called a béchamel sauce, or roux.)
Add grated cheese, the squeezed out spinach, and salt and pepper to taste, and stir until uniformly mixed.
5. Separate eggs, placing the whites into a large bowl, and the yolks into a small bowl. Be careful to not get any yolk at all into the whites, or they will not beat up later! If some falls in, use a spoon to gently scoop it out.
6. Beat the yolks and add to the béchamel, stirring well and quickly while adding them.
7. With an electric mixer, beat up the egg whites for several minutes until they form stiff peaks, as seen below. (They should stand up straight when you turn them upside down.)
8. With a rubber spatula, add about 1/4 of the whites to the béchamel/cheese/spinach mixture. Stir this together to lighten up the béchamel. Then, add the remaining egg whites to the béchamel sauce and gently fold them in. (See note below re: folding.)
9. Immediately place mixture into the prepared soufflé pan and put in preheated oven.
10. Bake about 30 minutes depending on the oven. The center should not be very jiggly - if it is, keep cooking longer. You can also stick a toothpick or knife into the center of the soufflé. If it comes out clean, it's done. Serve immediately. (Really! It'll deflate within a minute.)
Note: Fold does NOT mean stir! Use the spatula to scoop the mixture from the bottom of the bowl and fold it over onto the top of the mixture. This will eventually incorporate the whites with the béchamel. Do NOT over-mix - this will deflate the egg whites, preventing the soufflé from rising. The whole folding process should take no more than 90 seconds. It's okay if the mixture is not 100% uniformly mixed.