In a bowl, combine squash, quark/ricotta, egg, grated cheese, breadcrumbs, parsley, thyme, nutmeg, salt, and pepper. The filling should be moist but not wet — adjust with breadcrumbs if necessary.
Assemble strudel
4 Lay out one phyllo sheet on a clean towel. Brush lightly with melted butter.
5 Layer 5 more sheets, buttering each one as you go.
6 Spread the squash mixture along one edge in a log shape, leaving a 2-inch border.
7 Roll the strudel up tightly using the towel, folding in the ends. Place seam-side down on a parchment-lined baking sheet.
Bake
8 Brush top with melted butter.
9 Bake at 375°F (190°C) for 30–35 minutes, until golden brown and crisp.
Serve
10 Let cool slightly before slicing.
11 Sprinkle with pumpkin seeds if desired.
12 Serve warm with a simple salad or alongside a German beer.