Melt the butter in a pot and sweat off the onions, do not colour.
Add the milk and cook out till cooked through.
Strain through a fine chinos, and press out any remaining liquid.
Process with an immersion blender till a fine paste has been achieved, it may require passing prior to serving. If using a thermo mix passing will not be required.
Keep warm is serving immediately.
Scallop Method
Drain the scallops on kitchen paper, and season with salt.
Heat a pan, add a knob of butter and a little olive oil.
When the butter begins to foam, add a few scallops.
The pan should be hot enough to caramelize the surface not burn.
Once there is an even colour, flip over to the other side and colour.
Depending on the thickness of the scallop the cooking should only take a few minutes, please avoid over cooking.
Construction
In a small bowl, spoon in a small portion of the, hot, puree, and top with an evenly caramelized scallop. Drizzle with a flavored oil, I prefer a lemon oil, and garnish with micro cress.