Step 1

To Make the Choux Puffs: Adjust oven rack to middle position and preheat to 400°F (204°C). Line two aluminum half-sheet trays with parchment paper. Pipe a small amount of choux paste under each corner of parchment paper (the dough acts as a glue and keeps the paper in place as you pipe).

Step 2

To pipe the puffs, hold the filled pastry bag at a 90° angle, apply steady downward pressure, and pipe a 2-inch wide puff onto a tray. To stop piping, cease applying pressure and swirl the pastry tip away. Continue to pipe puffs about 3 inches apart, for a total of 9 puffs. Repeat with the second tray. To smooth the surface of any uneven puffs, dip a finger into cold water and gently pat down any bumps. If using, dust puffs evenly with powdered sugar.

Step 3

Bake both trays until choux is puffed, golden brown, and hollow feeling, about 25 minutes.

Step 4

Working quickly while puffs are still hot, gently insert the tip of a paring knife into the underside of each puff and rotate in a circular motion to create a small hole, about 1/4-inch in size.

Step 5

Return puffs to trays and place in the turned-off oven with the door partially open for 30 minutes.

Step 6

To Fill Piped-In Cream Puffs: Working one at a time, insert tip of pastry cream–filled bag into hole in each choux puff and begin piping with steady pressure until filled (you can tell because the puff will feel heavy and pastry cream will start to overflow the hole). Wipe away any excess pastry cream. Repeat until all cream puffs are filled. Serve immediately.

Step 7

Alternatively, to Fill Sandwich-Style Puffs: Using a serrated knife, slice each puff in half to create a top and bottom "bun.” Transfer your choice of filling (see notes section below for filling instructions) to a pastry bag fitted with a 1/2-closed star tip. Working one at a time, begin piping with steady pressure to generously fill the bottom half of each puff. Cover with the top half of each puff. Repeat until all cream puffs are filled. Serve immediately.