bolognese and burgers are completly completly different. you cant cook the sauce and the meat separatly as they rely on each other for flavour. if your sauce is that good why mess with it? you could season your mince with watever you use to make the sauce and cook them in the sauce, just like big burger shaped meatballs.this will allow the flavours to mix and develop.the thicker your sauce the less sloppy it will be. but hey wats wrong with being sloppy every once in a while!
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