Melt the butter in a pan, add the flour and stir for 2 minutes so the flour can cook.
Add the milk bit by bit and keep stirring so there's no lumps.
Add the cheeese and season with salt and pepper.
Leave on the heat while stirring. You want the mixture to be a thick doughball that comes off the sides of the pan.
Let this cool off so you can touch it with your bare hands.
Divide the filling into 40 grams portions. Shape each portion into a croquette. First cover with flour, then the eggwhites and lastly the panko. Repeat with the rest.
Freeze the croquettes for about an hour. You could keep them in the freezer for longer but then they'll be frozen through and through. You'll need to fry them for longer but there's a risk the cheese will seep out during frying (because of only the 1 panko layer)
Heat up the oil to around 180 degrees celcius and fry the croquettes in 2 minutes until golden brown.
Serve with chili jam