A cakeful of spoon
The mystery isn’t what the object is, but rather what the object is doing there. The last thing anyone would expect to find in their cake is an entire spoon. Did the baker forget to take the spoon out after pouring the batter in the bread pan? Or maybe they noticed but couldn’t be bothered to fish it out. That seems the more likely scenario.
However, it’s clear that they were looking for the spoon. You’ll see by how neatly the cake was cut. If they were real cake-eaters, they would have swallowed the whole thing in one gulp, spoon and all.