1. Place milk, eggs, 1/3 cup flour, butter, sugar, and 1 teaspoon salt in a large bowl; combine well using a whisk or an immersion blender. Mixture should be the consistency of heavy cream. If mixture is too thin, add more flour. Add herbs and let stand 15 minutes.

2. Place an 8-inch nonstick skillet or crepe pan over medium heat. Spray with nonstick cooking spray. Add a scant 1/4 cup batter and quickly swirl to coat the bottom of the pan. Cook until edges begin to dry, about 1 minute. Using your fingers or tongs, turn crepe, continue cooking about 15 seconds more, and then transfer to a plate. Repeat process with remaining batter, stacking each crepe on top of one another as you work.

3. Preheat oven to 425 degrees. Place all the mushrooms in a large bowl. Drizzle with olive oil and season with salt and pepper; toss to combine. Spread mushrooms on a rimmed baking sheet in an even layer; transfer to oven and roast for 10 minutes. Remove from oven and let cool slightly.

4. Place a crepe flat on work surface. Spread 1 tablespoon cheese evenly over three-quarters of the crepe. Top with about 2 tablespoons mushrooms. Starting with the covered portion, roll crepe toward the uncovered portion and place seam-side down on a baking sheet. Repeat process with 11 crepes and remaining cheese and mushrooms; reserve any remaining crepes for another use. Transfer filled crepes to oven until heated through, about 5 minutes.

5. Meanwhile, place mustard greens and spinach in a large bowl. Add 1/4 cup marmalade and season with salt and pepper; toss to combine. Divide greens evenly between 6 plates and top each with 2 crepes. Spoon any remaining marmalade over crepes and serve immediately.