• Preheat the oven to 400℉.
• Butter a 15 x 10 jelly roll pan.
• LIne the pan with wax paper and then butter the pan and dust it with flour. You may use a high quality baking spray instead of the butter and flour like Baker's Joy.
  Baker's Joy Spray
• In a medium saucepan on the stove, melt 4 tablespoons of butter over medium-high heat. Blend in the flour, salt and pepper with the flour to create a roux.
• Turn the stove to low heat and gradually add in the milk, stirring until smooth and thickened.
• Remove from the heat.
• Beat the egg yolks until thick and lemon colored.
• Gradually add the yolks to the milk mixture, whisking constantly so the eggs do not curdle.
• Beat the egg whites in a stand mixer or with an electric hand mixer set to high. The eggs should form stiff peaks and be well whipped.
• Gradually fold in the beaten egg whites to the yolk mixture using a rubber spatula and adding a small amount at a time until fluffy and combined.
• Pour into the prepared pan and spread out to the edges.
• Bake at 400℉ for 25 minutes until the eggs are puffed and golden brown.

Prepare the filling

• While the eggs are cooking, prepare the filling.
• Saute the shallots in 2 tablespoons of butter in a pot on the stove over medium heat.
• Add in the mushrooms and cook for 5 minutes.
• Take the mixture off the heat.
• Add in the spinach, mustard, nutmeg, and cream cheese. Mix well and set aside.

Finish

• When the eggs are done, cover the pan with a dish towel.
• Quickly turn the pan over so that the eggs are turned out onto the towel. Remove the pan.
• Take off the wax paper.
• Starting from the long side of the jelly roll pan and using the towel to help, roll the egg souffle into a log and let sit for 1-2 minutes. Unroll.
• Spread the filling onto the egg souffle.
• Re-roll and then place on a platter with the seam side down and hidden.