Preheat your oven to 450 degrees F. Generously grease your pan with butter (or oil) and place the pan in the oven as it preheats.
In the bowl of your KitchenAid mixer, combine the eggs and milk (room temp), sourdough starter, flour and salt. Add the minced garlic.
Mix just until the ingredients are combined, making sure not to over-mix.
With gloves on, remove the popover pan from the oven and set on a hot plate. Pour the batter into the popover pan - fill each cavity 2/3 full. The last popover might have less batter for a smaller popover - that is OK.
With gloves on, put the popover pan back in the oven. Bake for 20 minutes at 450; reduce the heat to 400 and bake an additional 5-8 minutes. Avoid opening the oven during this time.
Popovers should be dark brown and tall when done. If you aren't sure if they are done, give them an extra minute or two to ensure they don't fall when removed from the oven.
Serve fresh from the oven, with lots of butter.