Preheat the oven to 425 degrees.
Cut butter into small pieces and put a cube in each of the mini muffin tin cups.
Blend the ingredients on medium-high speed until they are combined and a bit frothy, about 1 minute. Transfer the mixture into a chef's squeeze bottle, if you are using one.
When the oven has reached temperature, heat the mini muffin tin with the butter for about 1 minute, until the tin is hot and the butter is melted.
Quickly remove the hot muffin tin and squirt the mini popover batter into each of the cups, filling about halfway. You can also use a spoon or a pouring device, but be sure to wipe the drips afterward. Quickly return the pan to the oven.
Cook the mini popovers about 12 minutes, until they have risen and are golden brown. It's better to avoid opening the oven, so try using the oven light to check on them. Allow the small puffs to cool about five minutes.
Serve in a tea towel-lined bowl along with any toppings, such as maple syrup, fruit compote, or powdered sugar.