Preheat the oven to 400°F.

Melt the butter in a saucepan over medium heat. Add the garlic and flour and whisk for about 2 minutes until the mixture is smooth and golden.

Gradually add the milk, whisking constantly to prevent lumps. Cook until the mixture thickens, about 5 minutes. Season with salt, onion powder, and pepper. Remove from heat.

In a separate bowl, whisk the egg yolks. Gradually whisk in a small amount of the hot milk mixture to temper the yolks. Then, slowly whisk the tempered yolks back into the saucepan with the remaining milk mixture.

In a clean bowl, beat the egg whites until stiff peaks form.

Gently fold the egg whites and the yolk mixture together until just combined. Pour into the prepared baking dish and sprinkle with Parmesan cheese.

Bake for 20-25 minutes or until the soufflé is puffed and golden. Serve immediately before the souffle begins to fall. Garnish with parsley.