The expression “one’s cake is dough” means one’s plans have miscarried; one is disappointed.
The proverb was old in the time of Shakespeare.
In Taming of the Shrew, Act I, scene 1, he has Gremio saying to Hortensio, both suitors of Bianca, “Their love is not so great, Hortensio, but we may blow our nails together, and fast it fairly out; our cake’s dough on both sides.”
Apperson reports the occurrence of the expression in the Prayers of Thomas Becon, 1559: “Or else your cake is dough, and all your fat lie in the fire.”
The allusion is obvious: when an oven does not reach a baking heat, one’s plans for a cake have miscarried.