Combine melted butter, sugar, and yogurt in a large bowl. Add eggs and whisk until evenly combined, then milk and vanilla. Sprinkle surface of batter with baking powder and salt and whisk to thoroughly disperse into the batter. Add flour and mix until it disappears.

Heat waffle iron according to manufacturer’s instructions and coat with nonstick spray. Cook your first waffle until it’s just beginning to color on top and the shape just sets but is not fully cooked through; in a tiny iron this takes 30 to 60 seconds. Remove these very soft waffles by first poking into the side of the waffle with a knife point, just to lift the edge. Then, use tongs to yank it out. Transfer waffle quickly on a cooling rack. Repeat with remaining batter.

Freeze waffles on the rack until completely solid, an hour or two, or overnight. Once solid, transfer to an airtight bag or container.

Place frozen waffles directly in toaster and cook until crisp and lightly browned outside. Alternatively, toast them in an oven heated to 400°F, either on an oven-safe rack for 8 minutes, or on a baking sheet, flipping waffles over midway for even toasting.

Serve hot with a pat of salted butter and drizzle of maple syrup and lots of fresh berries, or however you like your waffles best.