The knock wasn't exactly expected, but it wasn't unwelcome, either. Sirius found himself rather bored more often than not. Since Remus moved in ever so recently, that boredom had alleviated quite nicely, even though he did usually find himself face-to-face with a book rather than the actual man himself on most days. Through his train of thought, he set down the Muggle baking pan and unceremoniously dropped the half-nibbled square of semi-sweet chocolate to the kitchen counter.
Sirius cheerfully approached the flat's door, apron securely tied round his waist and grin on his face. The wards hadn't gone off so it could only be an Order member, or otherwise friendly face. Perhaps whomever it was might consider staying for his newest attempt at dessert. He was getting quite good at using the Muggle cooking contraptions, if he did say so himself.
Upon seeing Alice's familiar face on the other side of the door, he gave her a truly happy grin and ushered her inside with a barely contained: "Cheers! Bloody come on in! Just doing some manly cooking, don't mind the mess!"