Remove the puff pastry sheets from the freezer. Unwrap them and leave the sheets to thaw.

Peel and mince the garlic or push them through a garlic press

Peel and dice the shallots.

Place the unsalted butter in a large skillet over medium-high heat. when the butter has melted, add the minced garlic. Cook until the garlic releases its aroma.

Add the chopped shallots and cook, stirring occasionally, until they become soft and almost transparent.

Add the leeks to the pan and cook until they soften, stirring occasionally. Pour the water or vegetable broth into the pan.

When the liquid in the pan is simmering, add the shredded carrots, savoy cabbage, celery root, and parsnips to the pan and stir to coat them. Make sure everything is thoroughly combined.

Season the mixture with salt and freshly ground pepper. Be careful not to add too much salt as the cheese will add some saltiness to the mixture.

Remove the mixture from the heat, fold in the shredded cheese and let cool completely.

Line a baking tray with parchment paper and preheat the oven to 350 degrees F.

Take the puff pastry sheet and roll it out into a large rectangle shape, approximately 10 x 14 inches in size.

Sprinkle the bread crumbs on top of the puff pastry sheet, leaving about a one-inch frame around the edges.

If there is any remaining liquid left in the pan with the vegetables, drain it out and discard the liquid.

Evenly distribute the vegetable cheese mixture over the bread crumbs on top of the puff pastry rectangle, still leaving a one-inch frame around all the edges.

Separate the egg. Beat the egg white. Use a pastry brush to coat the puff pastry frame with the egg white, then fold the edges inward.

Working from the long side of the rectangle, gently roll the filled puff pastry into a log. Transfer the log to the baking paper, seam side down.

Cut the remaining puff pastry sheet into strips and lay them diagonally over the log or use your favorite shape cookies cutter to create shapes, adhere them to top of the strudel by using a dab of water on the underside of the shape to make them stick if they are not staying in place.

In a separate small bowl, whisk together the egg yolk and the milk and use the pastry brush to completely coat the outside of the strudel with the egg/milk mixture.

Place in the oven and bake for 35 – 40 minutes until golden brown.

Remove from the oven let cool before slicing and serving.