It's very similar to the Japanese Milk Korroke with a soft centre and crunchy skin.
I have taken photos of cut-open croquette but they came out blur, nevermind, this recipe is highly recommended, try it and taste for yourself!
The recipe is adpted from Bronwyn Shearer.
375 grams cooked meat (leftovers will do)
60 grams butter
50 grams flour
100 ml gravy
200 ml milk
10 grams gelatine/1 leaf gelatine leaf (make it soft in some water)salt
1 egg yolk
Lightly fry in the butter a very fine chopped onion, add flour, then gravy and milk. This will make the sauce.
Add the gelatine, egg yolk, pepper, nutmeg and salt. Then add the chopped meat. Spread the mixture on a pre-wetted plate. Let it cool (it will get thick).Use to spoons to form 10 equal croquette shapes.
Roll in breadcrumbs, then through egg white (whish egg white a bit first) and again roll in breadcrumbs.
Take it easy and don't crack the outer layer. Fry in hot oil.
P.S. If you don't want to use gelatine, then instead of 50grams of flour and butter use 75 grams of each.