Crack and whisk the eggs and sugar until smooth. Add in the milk, then the butter, lemon zest, and juice. Then add in the Flour and salt. Allow the batter to rest for 15 minutes.
Put at least a tablespoon or more butter or coconut oil in each of the popover or muffin tins. Place in the oven, on top of a sheet pan (in case any oil escapes), and heat until they melt. You want the oil to reach the smoking point.
Carefully, remove the pan from the oven. Fill the tins just over 3/4 of the way up. Sprinkle the berries evenly on top. Some will sink in. Pop back in the oven for about 20 minutes. They should be puffed up by this time. Then, drop the temperature to 350 and cook another 10 minutes.
Remove from the oven and allow to cool for a couple minutes. Then, carefully remove from the tins. Plate the popovers and sprinkle with powdered sugar. Serve as is, with syrup, a berry or chocolate sauce, ice dream, or whipped cream.
Notes
The cook time may vary a bit, depending on the size and shape of your tins. Standard popover tins hold about 3/4 to 1 cup batter each. Try setting your timer for 15 minutes, then take a peak at how they are coming along. But, try to avoid opening the oven door during the puff stage. Sometimes, I like to make mini popovers for hors d'ouevres. Top them with a meat and gravy. Obviously, they will take less time to cook. Start with a 10 minute timer, and go from there.These popovers have blueberries. But, you can substitute all kinds of flavors. Omit the sugar and vanilla for a savory base. Add Herbs or other fruit. Or, you can make them plain and fill with a pastry cream, a fruit compote, or lemon curd for dessert. Serve unsweetened ones with a Sunday roast or something like braised short ribs. have fun. Play with your food.