Preheat the oven to 425F degrees.

In a large bowl or pitcher, whisk together the flour and milk. Whisk in the eggs one at a time.

In a pot, melt the butter over medium heat. Add the mushrooms and spinach and sauté until tender. Let cool for 5 minutes.

Stir the spinach and mushrooms into the egg mixture.

Spray 6 ramekins with non-stick cooking spray and set on a sheet pan. Add about a half cup of batter to each ramekin.

Place in a 425-degree oven and bake for 20 minutes. Serve immediately.