• 2 tablespoons butter
• 1/4 cup extra-virgin olive oil
• 1 large shallot, chopped finely
• 2 cloves garlic, chopped finely
• 1 1/2 pounds assorted fresh mushrooms sliced
• Sea salt and black pepper
• 2 tablespoons each finely chopped thyme, tarragon, flat-leaf parsley and chives
• 1 large egg plus 1 large egg yolk, beaten together
• 1/2 package (1 sheet) puff pastry, thawed
• 1 large egg plus 1 teaspoon water beaten, for egg wash
1. In a large skillet, heat butter and olive oil. Add shallots and garlic and soften. Add sliced mushrooms. Season with salt and pepper and cook over low heat until tender. If juices exude, raise heat and cook until they evaporate. Stir in 3/4 of herbs and remove from heat. Spread mushrooms on a pan to dry and cool completely, about 30 minutes.
2. When dry and cool, transfer mushrooms to a large bowl and combine with whole egg-egg yolk mixture.
3. Place puff pastry on a parchment-lined baking pan. Roll to remove any creases and to elongate slightly. Brush surface with egg wash and sprinkle on remaining herbs. Spread mushrooms evenly over first 3/4 of pastry, leaving a 1-inch border around edges.
4. Flip over edge nearest to you and lay it on the top 1/4 so that puff pastry touches puff pastry, encasing mushrooms completely in a cylinder. Don't roll in pinwheel fashion as for strudel because the puff pastry in the interior will never bake and it will become gummy.
5. Move strudel to center of baking pan and tuck in ends. Brush entire surface with egg wash. Using the back of a knife, run criss-cross pattern over strudel. If desired, add cut-out leaves, flowers and vines from a portion of the second sheet of puff pastry (frozen grocery store puff pastry typically comes two sheets to a box). Egg wash the designs.
6. Bake until golden brown and puffed, anywhere from 15 to 30 minutes, depending on your oven. Let rest at least 2 minutes before slicing with a serrated knife.