I made this for an appetizer over the weekend. It was a big hit & it's still good two days later.

Leek and Asparagus Strudel

3 Tbsp plus 1/2 cup cold unsalted butter, divided use

2 medium leeks (white & pale green parts only), sliced

1 lb asparagus, trimmed & cut diagonally into 1-inch pieces

4 oz Gruyere cheese, shredded (about 1 cup)

3 extra large eggs, divided use

3 Tbsp fresh dill or 1 tsp dried

2 Tbsp fresh lemon juice

1/2 tsp salt

1/2 tsp freshly ground black pepper

9 fresh or frozen phyllo sheets, thawed (17x12 inches)

Melt 3 Tbsp of the cold butter in a large heavy saute pan over medium heat.

Add the leeks & saute until tender & translucent, about 6 min.

Add the asparagus & saute until bright green & crisp-tender, about 3 min.

Remove from the heat & set aside until the asparagus mixture is room temperature.

Stir in the cheese, 2 eggs, dill, parsley, lemon juice, salt & pepper.

Put an oven rack in the middle of the oven & preheat to 350 degrees.

Melt the remaining 1/2 c. butter. Brush a large heavy baking sheet with some of the butter.

Lay one phyllo sheet on a work surface & brush lightly with butter. Repeat this using seven more phyllo sheets & melted butter.

Spoon the asparagus mixture on the phyllo stack, forming a 12x3 log & leaving a 2-inch border of phyllo on each short side.

Fold the short edges in.

Fold 1 inch of the long side furthest from you toward the filling.

Beginning at the longside closest to you,roll up the strudel tightly to enclose the filing completely, as for a burrito, making sure the ends are tucked in & ending with the 1-inch seam on the bottom.

Transfer the strudel to the baking sheet, seam side down, in the center of the prepared baking sheet.

Brush some of the remaining melted butter over the sides & ends of the strudel.

Brush the remaining sheet of phyllo with the remaining melted butter. Cut the phyllo sheet into 4 squares.

Gather each phyllo square together to form loose rosettes.

Beat the remaining 1 egg with the remaining melted butter in a small bowl to blend.

Lightly brush the top of the strudel with the beaten egg to help keep the rosettes in place. Set the rosettes atop the strudel.

Bake uncovered until golden brown, 30-55 minutes. (A small amount of filling may leak out.) Let cool for 20 minutes. Cut the strudel crosswise into slices & serve.

Do Ahead: The strudel can be assembled, covered & refrigerated 1 day ahead.

NOTE: Unstead of phyllo, I used 2 sheets of frozen puff pastry, thawed. I placed one sheet on the baking sheet, spooned the asparagus mixture on it, & topped with the second sheet of puff pastry. I pinched all the edges together. I assembled the strudel the night before.

Source: Celebrating with Julienne cookbook

Here is a link that might be useful: Celebrating with Julienne cookbook