Place milk in a bowl and sprinkle with yeast. Let stand until foamy, 4 to 5 minutes (if yeast does not foam, discard and start again). Add 1/3 cup brown sugar and 1 cup flour. Beat with an electric mixer's dough hook on low speed until combined for a couple of minutes. Beat in salt, 1 tsp of the pumpkin pie spice, and 90g of the butter until smooth, 1 minute. Beat in 3/4 cup of the pumpkin until smooth, 1 to 2 minutes.

Add eggs, one at a time, beating until blended after each addition. Gradually beat in remaining 3 3/4 cups flour just until combined, 1 minute. Increase the mixer speed to medium and beat until dough forms a loose ball and begins to pull away from top of bowl, about 1 minute (dough will still stick to bottom of bowl). Continue to beat until dough is smooth and elastic, 3 to 5 minutes.

Place dough in a separate, greased bowl. Cover with a clean dish towel and let rise in a warm place until doubled in size, 45 minutes to 1 hour.

Stir together remaining 110g butter and 1/4 cup pumpkin in a bowl. Stir together remaining 1/3 cup brown sugar and 1 teaspoon pumpkin pie spice in a second bowl.

Punch down dough and turn out onto a well-floured work surface. Roll to a 12-by-16-inch rectangle. Spread butter mixture over dough, leaving a 1/2-inch border around edges. Sprinkle with brown sugar mixture, pressing gently to help adhere. Roll up dough, starting at one long side. Trim both ends of dough.

Line a large rimmed baking sheet with parchment paper. Using a serrated knife, cut dough into 12 equal slices. Arrange on prepared baking sheet. Cover with a clean dish towel and let rise in a warm place until puffed, about 30 to 40 minutes.

Preheat oven to 175°C/350°F. Bake until golden brown and cooked through, for around 20 to 25 minutes. Cool on a wire rack for 10 minutes. Serve warm and enjoy!