Preheat the oven to 400ºF. (not convection/ fan-assisted). Brush your popover or muffin tin generously with softened butter. Set aside.
For the puffs, add the 2 Tbsp melted butter, eggs, milk, vanilla, salt and sugar in a blender and blend for a few seconds. Add the flour and blend for about 10 seconds, just until smooth.
Divide the batter among 6 popover cups or 9 muffin cups, filling each 1/2 to 2/3rds full. Top with 3 blackberries (or 2 if using muffin cups).
Bake for about 35 minutes, or until the puffs are deep brown.
Remove from the oven and allow to cool in the pan 4-5 minutes, then remove the popovers from the pans and set them on a cooling rack. You may need a small knife or spatula to help pry them out.
For the sugar coating: While still warm, thoroughly brush each popover all over with melted butter, then sprinkle generously with sugar. Let cool on the wire rack.
Notes
Tips!
If you don't have a popover pan, you can use a regular muffin pan. You will get about 9 small, muffin-sized popovers.
You could easily substitute raspberries, blueberries or strawberries for the blackberries here.
Even though the berries will sink into the batter, as they bake, they will be pushed up to the surface again and will be somewhat loose after baking. Don't worry if the blackberries fall off as you are brushing/sugaring. Just put them back where they belong.
Be sure to read the notes above this Recipe Card for more tips on making this recipe.