Popovers from Homemade Fun

I was so excited to get this book just in time for summer-fun for me and Chloe:

There are tons (101 to be exact) of activities to do inside, divided up into various categories: sewing, papercrafting, and baking, to name a few. Since Chloe and I love to cook up a yummy snack (and before the heatwave hit us with full force!), I flipped right to the Popover recipe. With 4 ingredients and 4 steps, I was sure it was something we could do before losing focus...
Whisking the eggs...
Adding the flour...
Pouring into ramekins (the recipe calls for popover cups...never heard of such a thing! Apparently, muffin tins will work as well, but I didn't find this out until after)
Watching excitedly as the popovers begin to "pop."
...and, here they are--our quickly sinking popovers :( They looked so pretty when I first took them out, but quickly deflated. I also read later that I should have poked a hole in the top to allow steam to escape once I took them out of the oven (would have been good info for the recipe).
They ended up being eggy-muffins instead of popovers, but this was my first time making them. Others tricks I found online were to use room-temp ingredients and mix them quickly in a blender to get lots of air incorporated into the batter. We'll try again in a few days--can't say I mind making them again, they were so quick and easy!