For topping: In a small bowl, combine pepitas, sugar, and cinnamon. Drizzle with melted butter, and stir to combine.
For brioche: In the bowl of a stand mixer fitted with the paddle attachment, combine ⅓ cup warm water, 1 tablespoon sugar, and yeast. Let stand until foamy, about 10 minutes. Add 1 egg and 1 cup flour, and beat at low speed until combined.
Cover loosely with a tea towel, and let stand until doubled in volume, about 30 minutes.
Add remaining approximately ¼ cup sugar, orange zest, salt, remaining 2 eggs, remaining 2½ cups flour, and pumpkin; beat at low speed until combined, scraping down sides of bowl as needed. Increase speed to medium, and continue to beat until dough is smooth and elastic, 2 to 3 minutes. Reduce speed to low, and slowly add softened butter by the tablespoonful.
Coat a large bowl with cooking spray. Scrape dough into bowl, turning to grease top. Cover, and let stand at room temperature (75˚) until doubled in size, at least 2 hours.
Turn out dough, punch down, and divide in half. Cover loosely, and let dough stand for
minutes.
Coat 2 (8x4-inch) loaf pans with cooking spray, and line with parchment paper.
Working with the first half of dough, divide evenly into 8 balls. Arrange balls on prepared pan. Repeat with remaining half of dough. Cover, and let stand in a warm (75˚), draft-free place until dough is puffed, 60 to 90 minutes.
Preheat oven to 400˚.
Brush risen loaves with lightly beaten egg, sprinkle with topping, and bake for 15 minutes.
Reduce oven temperature to 350˚, and continue baking until brioche is golden brown and a wooden pick inserted in center comes out clean, 30 to 35 minutes. (If bread begins to brown too quickly, tent loosely with foil, and continue baking.)
Recipe by Victoria at https://victoriamag.com/pumpkin-brioche-recipe/