Preheat the oven to 400 degrees F.
Using a pastry brush, coat 8 muffin cups with 1 tablespoon of the melted butter and put the tin in the oven for 5 minutes. Meanwhile, mix the eggs in a blender until light yellow. Add the warmed milk and blend. Add the flour, salt and remaining melted butter, and blend until smooth. Pour the batter into the warmed muffin tin and return it to the oven to bake until golden, about 35 minutes. Remove from the oven and serve warm.