This whole time he's been bullied by his sister and had bad things happen to him so often that i fully expected those muffins to be eaten by someone else. Tragic
As long as he kept them in his dimensional storage, it would have been impossible for anyone to get their hands on them. He should have done it anyway to keep them fresh. But then again, this story indeed does make a point of spoiling his plans, so who knows. He might have taken them out once to remind himself of how many there were, and at that moment his mother, sister, or a maid would have walked in, unannounced, and claimed them all, no questions asked or excuses given. It would have been 100% fitting for this series.