With TM running at speed 7, drop the shallot through the hole in the top. Stop the TM, add the butter, and cook at 100C for 4 minutes at speed 1. Add the flour and cook for 2 more minutes at 100C, speed 4. Always scraping down as necessary.
Add the milk.
Process at 100C for 5 minutes at speed 4.
Place the bread cubes in a medium sized bowl, and pour the sauce over them. Toss to coat and stir in some of the bread. Allow to cool.
While the sauce and bread cools, melt the remaining butter in a saute pan and cook till the butter just starts to turn brown. Then add the crab meat and toss.
Add the mayo, lemon juice, salt, and pepper to the bread and sauce. Stir to combine.
Add the crab meat and butter. Fold gently to incorporate the sauce, but not break up lumps of crab.
Distribute the mixture between 4 heatproof ramekins. Sprinkle with paprika.
Bake in a 450F (230C) oven for about 10 - 15 minutes or till bubbly and nicely browned on top.