In a large bowl, combine the pumpkin, nuts, sugar, breadcrumbs and cinnamon. Stir to combine.
Preheat oven to 350F. Line a baking sheet with parchment paper or silpat.
Open the phyllo dough and place on a working surface. Take 2 sheets out, brush with butter, and cut them into 4 stripes, along the shorter side. Add about 1 tbsps of filling on one end. Fold one corner of fillo diagonally across to opposite edge to form a triangle. Continue to fold triangle onto itself. Brush outside with butter.
Place on the baking sheet and bake for 20-25 minutes, until golden.
Take out of the oven and let them cool to room temperature. Dust with powdered sugar and cinnamon.