Choux pastry (pâte à choux) makes an appearance in many episodes of the Great British Baking Show. It sounds relatively simple: combine water, butter, flour, and eggs over heat, then pipe into the shape you desire. The high moisture content of the dough (it's really very close to a batter) turns into steam when the choux is heated, and causes the dough to expand or puff out, to create the puffs or tubes desired. GBBO has also shown me that it can be tricky to make. The hard part is adding the eggs: you measure out the eggs by weight, but depending on relative humidity and other conditions, you don't necessarily add them all. This means that a recipe that works in one instance may not work at another time or place. More than one Bake Off contestant has had to try multiple times in an episode to get the pastry made correctly.
I was nervous, so I did a fair amount of reading online before I started. There are a lot of resources, but the most helpful one I found was an excellent and detailed guide by the Flavor Bender (linked above). I took the guide's suggestion of beating the eggs so the I could add half an egg if needed. I used a small ladle to add roughly half an egg at a time and was able to get to the correct consistency (again, described well in the guide).
I didn't have the correct size of piping tip to pipe the choux, so that caused some small problems. I think the problems I had with a few of the individual pastries not rising quite right happened because of inconsistent piping.
I have made creme patisserie (creme pat) before, so I didn't really have any trouble here. I didn't temper the eggs sufficiently (I should have added more of the hot milk mixture to the egg mixture before fully combining them) so the eggs scrambled slightly. You can't really taste it, and since I am not on a baking competition, I chose not to remake the cream.
This is the point where I got over-confident. I knew I could take a shortcut by microwaving the cream instead of heating on the stove (I've done both), so I did. Unfortunately, I didn't keep a close enough eye on the microwave, and lo--Mount Creamsuvius did erupt! The cream-sposion necessitated an excess of paper towels, a stool, and a truckload of patience. (If you look in the picture below, taken at about 90% clean up, you can see some of the cream spattered about the kitchen.) It turns out that hot cream has no trouble decorating the interior of your microwave, and it is equally adept at escaping through any small cracks between the microwave door and body. I did the second, post-clean-up batch of cream on the stove with no trouble.