Whisk in the warm milk. Then, sift in half of the flour mixture at a time, whisking until smooth to prevent a lumpy batter.
50 grams whole milk
Gradually whisk in the warm melted butter, a third at a time until smooth.
125 grams unsalted European Style butter
Cover the bowl with plastic wrap and refrigerate for 2 hours. *Batter can also be refrigerated overnight, with the plastic wrap touching the batter to prevent a skin from forming.
Preheat oven to 400℉ (200℃) conventional or convection oven.
Prep the Pan
Generously brush the softened butter across each shell cavity, getting into every groove. Sift flour over the butter and then tap out any excess.
butter, all purpose flour
Place the pan in the fridge for about 10-minutes for the butter to firm.
Remove batter from the fridge and transfer to a piping bag for easing filling. Pipe batter into each cavity filling up to 90% or 3/4 full.
Place the filled pan in the freezer for 10-15 minutes for an extra cold pan and batter before placing in the oven. The temperature shock of the cold batter in a hot oven will create that perfect hump.
Bake
Place pan on the middle oven rack. Bake for 2 minutes, then reduce temperature to 375℉ (190℃) and bake for an additional 6-7 minutes.
The center of each madeleine should have a raised bump and a golden brown crust will form around the edges.
Remove pan from the oven and immediately tip madeleines out onto a wire rack to cool completely.
Wash the pan and then prep it again with butter and flour. Repeat with remaining batter.
Lightly dust cooled madeleines with powdered sugar and serve.
Video
Notes
DO NOT SKIP CHILLINGTIME: What gives French Madeleine's their signature bump is the reaction of cold batter going into a hot oven. The batter also needs the original rest to relax the gluten, thicken the batter, and develop in flavor. I've found that a quick freeze of the pan filled with batter creates a lovely tender cake with a high bump and crisp edges.