You just will not get the marzipan to ooze into the cake batter if it starts off fridge-cold. In dire straits, I have cubed it and given it a quick whirl in the microwave. And if you wanted to replace the vanilla extract with the zest of an orange, I wouldn't mind in the slightest.
Nigella's Quadruple Chocolate Loaf Cake - I've made this once every couple/few months for years, except changing the sour cream for yogurt/greek yogurt, and it's so super chocolately. Never even thought about pinning it as I've not needed a recipe for years, so remembered when I saw other pins! RLI firmly recommends!!
For me, a chocolate cake is the basic unit of celebration. The chocolate Guinness cake here is simple but deeply pleasurable, and has earned its place as a stand-alone treat. (Photo: Suzy Allman for The New York Times)