Pumpkin Pau - Failed

First attempt at pau making. Tried out this healthy pumpkin pau recipe but am not very happy with the results. The filing is great, but my bun didn't taste as soft and fluffy as I would like, and it looked so flat! Gotta improve on my pau kneading and shaping skills.

Will definitely try this again as I believe this will be a very delicious pau, if only I could get it right.....

Ingredients

Pau
60gm sugar
90gm pumpkin puree
1 tsp instant dry yeast
150gm pau flour
1 tsp double acting baking powder
10gm butter

Pumpkin Filling
300gm pumpkin puree
30gm sugar
1 tsp cornstarch

Method

1. Prepare pau dough. Combine sugar, pumpkin puree and yeast.
2. Combine pau flour, baking powder and butter. Mix to form crumbs.
3. Pour (1) into (2) and mix to form a dough.
4. Knead dough until it is smooth and no longer sticky.
5. Let dough proof in a warm place until double in size.  
6. Cook pumpkin filings ingredients until thickens and use 2 teaspoons to form into little balls and place on a lined tray. Chill until time of use.
7. Punch down dough after it has doubled. Knead it for 2 minutes and divide dough into 12 pieces.
8. With lightly floured hands, take one piece of dough and flatten it, making it thinner at the sides.
9. Place one piece of filling, round side down onto flattened dough.
10. Wrap and seal bun.
11. Let buns proof (covered) for 45 minutes and steam on high heat for 12 minutes.