Complex sentence: When enemies are defeated, they drop various items of ingredients (food) that, after completion of a stage, can serve to replenish one's health meter by mixing two ingredients to create a meal (hence the name "gourmet" in the title).
Split into simpler sentences: When enemies are defeated, they drop various items of ingredients (food) that, after completion of a stage, can serve to replenish one's health meter. This is made possible through a process of mixing two ingredients together to create a meal (hence the name "gourmet" in the title).