Bowser's Sourpuss Bread

From the Super Mario Wiki
Mario with Bowser's Sourpuss Bread
“You know what they say: All toasters toast toast!”
Mario, Hotel Mario

Bowser's Sourpuss Bread is a brand of bread that was used in Hotel Mario, in which it was being toasted by too many toasters in Roy's HardBrick Hotel, where it caused electrical flickering. As well as his name being on the product, the packaging includes a distinct Bowser logo, implying Bowser's forces manufacture this bread.