There are many Cavacas recipes that come from the 9 islands that make up the Azores island group just off the west coast of Portugal. Most families have their own favorite recipe, some light and airy and some with a more robust flavor. This is an easy (and delicious) recipe to start with. You can change the icing flavor if you wish, and use extracts in place of the lemon zest and lemon juice. Cherry and vanilla are good. But the lemon icing is great, too.
Preheat oven to 350°F. Thoroughly grease regular size muffin tins (any sticking can ruin the entire popover); set aside.
Using an electric mixer, beat the flour, oil, milk, eggs and vanilla on medium-high for at least 20-25 minutes without stopping. Fill 24 greased muffin cups about half way.
Place muffin pan on the middle rack in preheated oven, and bake for 45-50 minutes without opening the oven door during baking (or they will collapse). Cool slightly in pan. When cool enough to handle, gently remove popovers from the muffin pan.
Stir together the confectioner's sugar, lemon zest and milk until smooth. Spread or drizzle the glaze on the top of each popover while they're still slightly warm.