Place all dough ingredients in the bowl of an electric mixer fitted with the paddle attachment. Mix for 2 minutes on low speed and then increase speed to medium.
Knead dough for 10 minutes, pulling dough off paddle once or twice, until dough takes on a stringy appearance. Wrap and let rest at room temperature for at least 1 hour before using. If chilling, let dough come fully to room temperature before pulling
For filling, stir ricotta and garlic, cut brie into small pieces and beat vigorously into ricotta. Stir in pepper and chill.
To assemble strudels, preheat oven to 375F (190C) and line a baking tray with parchment. Lay out a small tablecloth over work surface and sprinkle cloth with flour. Cut dough into 3 pieces. Coat hands with flour and press flat the first piece of dough. Carefully start dstretching the dough into a square shape, pulling gently and evenly (using the back of the hands is easiest). Use the table or counter edge to secure the dough once it reaches (these are small strudels, so won’t take up the whole table). Strudel dough should stretch to about 16-inches by 24 inches. Brush the entire surface lightly with butter and sprinkle with ½ cup breadcrumbs. Spoon a third of the cheese filling along one short and of the strudel and sprinkle 1 cup of walnuts over the cheese and a little over half of the dough. Trim edges of strudel dough. Lift dough up using the tablecloth from the cheese-filled end and let the pastry roll itself up as you lift the cloth. Pinch the ends closed and lift onto prepared tray. Brush with eggwash, sprinkle with poppy seed sand repeat with remaining 2 pieces of dough.
Bake strudels for 18 to 25 minutes until rich golden brown. Cool for 15 minutes before slicing.
Serve strudel on its own or as an appetizer with a salad, or as a starch as part of a main course.